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Dude, blades before babes, you know what I'm saying?

–Sumarbrander to Frey, in The Sword of Summer.

Sumarbrander, also known as the Sword of Summer, or Jack, is Magnus Chase's sword and companion, formerly owned by his father, Frey. He is said to be the sharpest sword in the Nine Worlds. At the sword's request, Magnus renames him Jack after becoming his master.


Sumarbrander is a magical sword, originally owned by the Vanir god Frey. Frey fell in love with a frost giant, Gerd, who he was not allowed to marry. Frey ended up trading his sword to Skírnir, his servant, to kidnap Gerd and bring her to him. It sunk on a Norse ship in Boston, where it was found and renewed by Magnus Chase. Sumarbrander ended up being betrayed by its original master, although he continued to obey Skirnir. Sumarbrander is one of the most famous swords in Norse Mythology.

Magnus Chase and the Gods of Asgard

The Sword of Summer

Magnus Chase retrieves the sword from the bottom of the sea before Surt attacks him. Magnus comments that it didn't really look like a sword - it looked more like a lead pipe and was corroded, crusted with barnacles, and covered in mud and slime. He renews it during the fight with Surt. After he dispels Surt with the sword, he loses it at the bottom of the ocean after dying in the human world. After retrieving the sword by bargaining with the sea goddess Ran, the sword turns into a pendant with the rune of Frey on a chain.

When visiting Freya, Magnus learns about Sumarbrander's past with its original owner, Frey. Freya tells Magnus that the sword has "special abilities" that he will need to learn to master.

While running away from Eitri Junior, Magnus pulls out Sumarbrander, who he then finds out has the ability to talk. After disarming all the attacking svartalves, Sumarbrander is given the name Jack. Before they flee Nidavellir, Jack tells Magnus that if he returns him to pendant form, he'll feel as if he did everything that Jack just did, which could cause him to pass out or die.

He was then used to track down Thor. When Magnus and Samirah al-Abbas get Geirrod's daughters to admit they tried to kill them, he scrambles their brains.

When they reach Lyngvi, he desperately tried to get to Surt. After Magnus snaps him out of it, he ties the rope Andskoti to Jack to tie up the Fenris Wolf. Magnus then uses Jack to heal Halfborn Gunderson.

When Jack and Magnus are greeted by Frey, he desperately tries to attack the lord of Alfheim while Magnus restraints him.

The Hammer of Thor

Magnus unsheathes Jack when Otis is killed by an assassin. He went on to attack their target while Magnus was hoisting himself onto a roof. He fought with the assassin and managed to cut into their thigh. Jack was disappointed that he could not cut through the assassin's sword, but Magnus managed to cheer him up.

When Magnus returns to his room in Hotel Valhalla he asks Jack to ask him about a mark that appeared on a picture and pottery. Jack tells Magnus that Mjolnir can be taken if someone has the numbers and the strength to do so. T.J. pops in to tell Magnus it's time for battle practice. Magnus was surprised to learn that the two of them hung out the night before. Jack skips out on battle practice due to a date with a polearm. After dinner, he flies Magnus over to Sam and he starts singing Selena Gomez

He is summoned in a wights tomb to see if Mjolnir was in an iron coffin. He eagerly asked if he could open it. When he learns that the sword Skofnung was inside the tomb he became excited (mostly because he thinks Skofnung is hot). We also learn from Jack that the Skofnung sword is female. He also voted to try and delay the fight. He helps Magnus fight the draugr and after they win he requests to take Skofnung with them. On the way to the airport he asks if Magnus can unsheath Skofnung, but his wielder refuses and tells him to go back to pendant form.

In Alfheim, he is summoned by Magnus to guard him while he helps Hearthstone search for Andvari. He also explains to Magnus the side effect of Thor's rune. He helps interrogate Andvari into giving them his treasure.

At the party he destroys the Nøkk's violins and slices through the utility belts of two police officers. He senses a weak point between the worlds and cuts open a portal so they can escape.

At Randolph's mansion, he vibrates like he is either excited by the weapons, or nervous about being in the location.

In Jotunheim, he helps Blitzen add magical properties to Tiny's bowling bag. When Blitzen is finished, Magnus takes hold of him, before passing out from exhaustion.

When they meet up with Thor he tells the thunder god what they learned about his hammer and high fives his staff when they form a plan.

At the wedding, he is summoned but turns inanimate once Skofnung is drawn outside of its conditions. He is depressed after the battle.

The Ship of the Dead

Jack pulls Magnus to shore when he jumped of the USS Constellation. He also starts to flirt with Riptide, calling the sword she. Jack is upset when Percy sheathes Riptide, so he turns back into a pendant. He is summoned again when a wolf is trying to break into the Chase Mansion, and is upset that he was not needed.

Magnus summons him to help fight the Nine Billow Maidens. He returns to pendant form after the fight and tells Magnus to complement Njord's feet.

During the voyage, he and Magnus spar with Sam to help her resist Loki's influence. After training, Magnus reattaches him to his necklace and passes out.

He is summoned to watch Alex while Magnus heals T.J. during their fight with Hrungnir. After T.J. stabs the giant in the heart, he warns them that it could explode.

He is summoned by Magnus to help him kill Alderman. Jack is more concerned with Magnus getting injured and being left behind than his own safety. He and Magnus hide by the entrance of Alderman's cave and he tells Magnus when it is time to strike. He gets lodged in Alderman's chest cavity, but is freed by Hearth and removes Alderman's heart at Hearth's request. He watches Hearth roast the heart and is shocked when Magnus accidentally destroys it and tastes the blood. He tells him he should not have done that before going back to the Big Banana.

He is summoned to help open the doors to get the mead. He and Magnus fight one of the giants while the other goes after Sam and Mallory. They murder him with a murder of crows and head back to the Big Banana.

He helps de-ice the big banana until they decide to walk to shore. He checks the ice for weak points along the way. The group is invited in by Skadi to explain themselves.

Magnus summons him to guard him when the hoard notices them. He is flung away when Magnus unleashes the peace of Frey. He is annoyed that Magnus used the peace of Frey when he returns to see the flyting. He is annoyed that Magnus left him out of his speech until he promises to have Bragi write him an epic. The escapes with the rest of the group just as the harbor freezes over. He tells this to Frey when they meet with him and the rest of the major gods in Vigridr.

9 from the Nine Worlds

I Play with Fire

While staying with Alex Fierro during Magnus‘ visit with Annabeth, he warns her of that Surt is planning something. When Alex tells him to come with her, he says he cannot due to his fate being to go to Surt during Ragnarok. He brainstorms with Alex about not getting caught by going alone and constantly shapeshifting.


Jack is a voluble sword and is very sarcastic. He likes to flirt with other weapons, and is depressed when they don't return his affections. He also holds a deep grudge against Frey for giving him up for the sake of love.


In its dormant form, it's a small white runestone emblazoned with a black symbol: the Fehu rune- the symbol of Frey on a golden chain. The stone is magnetically attached to its chain, so it can easily be pulled off, and as soon as it is, the stone grows into a sword with a leather-wrapped grip that feels warm and comfortable to the hand. The pommel, a simple polished steel oval, helps counterweight the thirty-inch blade, which is double-edged and rounded at the tip, more for hacking than stabbing. Down the center of the blade, a wide groove is emblazoned with Viking runes that shimmer in a lighter shade of silver, as if they'd been inlaid while the blade was forged.


Jack is a sentient blade; he has the ability to speak and understand human language (although, as he says, he can't speak Alf Sign Language, because he has neither hands nor eyes).

He is able to fly his wielder across short distances, however they do pass out soon afterwards.

Jack is also very effective against the jötnar, and he can fight them on his own. He is also the only thing capable of cutting through Gleipnir. Whenever the holder of the blade retrieves him after an action, they receive the consequences of the action that Jack has performed.

He is also capable of cutting the fabric of reality opening portals to the Nine Worlds. Jack also has the power of a paradox material as he is a "weapon that wasn't designed to be a weapon", a sword that is best used if you let go, meaning he is not just the sharpest sword in the Nine Worlds, but also the strongest. It has also been stated that Jack has a horrible singing voice and it's suggested it could be a form of torture. He also dates with hot magical weapons.



In The Ship of the Dead, on the boat with Percy, Annabeth, Magnus, and Alex, Jack is excited to see Riptide, saying she's famous. He then goes on to flirt with Riptide. He appears to be 'heartbroken' after he is separated from her.


According to Jack, he was going on a date with a hot spear.

Magnus Chase

Jack is incredibly loyal to Magnus, offering him advice on how best to wield him and encourages the son of Frey to fight on his own during Battle Practice.


Jack resents the god of summer for giving him up.


Jack fears the lord of Muspellheim as being close to him with start Ragnarok.

T.J.'s bayonet

Jack went clubbing with T.J and his bayonet


The sword‘s Old Norse name means “summer-sword”, a combination of the words sumar (n.) (cognates: OE sumor, OHG sumar, Old Frisian sumur), akin to modern English summer, and brandr (n.) (descendants: Modern English brand, Icelandic brandur, Swedish brand, Danish brand).


  • When wanting to be named, he mentions that he never liked the name Sumarbrander because it was so long.
  • Jack's name came from when Magnus says "! don't know jack –", which meant that he didn't know anything.
  • After Sumarbrander begins to speak in The Sword of Summer, his voice is described "definitely male" and is then on described using male pronouns.
  • Sumarbrander is destined to become Surt's possession and kill Frey during Ragnarök.
  • In The Sword of Summer, when discussing what form should Jack become when not a sword, Magnus Chase suggests a pen. Jack comments that a pen sword is 'the stupidest thing he's ever heard'. This is a nod at Percy Jackson's sword, Riptide, which becomes a pen when "capped".
    • In The Ship of the Dead, when Jack sees Riptide for real, he tells Magnus that a pen sword wasn't a stupid idea like Magnus thought, even though Jack was the one who thought that.
  • In The Ship of the Dead, Jack reveals he met Hercules, indicating the Norse gods might be older or as old as the Olympians.
  • Jack is a paradox, being a "weapon that wasn't meant to be a weapon" and a "sword best used by letting go".
  • In The Hidden Oracle, Apollo mentions having met a smoking hot god in a Stockholm tavern whose sword wouldn't stop talking. The weapon is assumed to be Sumarbrander and the God is most likely Frey.
  • Curiously, the runes on Jack's blade don't seem to translate to anything in particular. When read vertically (in Anglo-Saxon fuþorc), it roughly reads /æ(ː)æ(ː)ɑe(ː)i(ː)f/, or 'aaaeif'.
  • Jack has the entire cast album of Jersey Boys memorized.
  • By his ability to cut the fabric of reality to open portals to the Nine Worlds, Jack is similar to Æsahættr, the Subtle Knife from Philip Pulman's His Dark Materials series, a blade with edge so sharp and subtle that it can cut windows (portals) between realities.
Magnus Chase and the Gods of Asgard
Core Series: The Sword of Summer | The Hammer of Thor | The Ship of the Dead
Main Characters: Magnus Chase | Alex Fierro | Blitzen | Halfborn Gunderson | Hearthstone | Loki | Mallory Keen | Samirah al-Abbas | Sumarbrander | Thomas Jefferson Jr.
Secondary Characters: Randolph Chase | Gunilla | Natalie Chase | Amir Fadlan | Alderman
Minor Characters: Annabeth Chase | Frederick Chase | Helgi | Hunding | Vala | Junior | Lars Alhstrom | Stanley | Inge | Percy Jackson | Stan | Alviss | Miles | Wildflower | Sunspot | John Henry
Norse Gods: Freya | Thor | Balder | Ullr | Frey | Odin | Heimdall | Vidar | Sif | Frigg | Tyr
Minor Gods: Skírnir | Mimir | Ran | Hod | Hel | Sigyn | Aegir | Nine Billow Maidens | Njord | Kvasir | Holler | Forseti | Glum | Lofn | Sól | Idunn
Jotnar: Surt | Gerd | Norns | Utgard-Loki | Harald | Ymir | Geirrod | Gjalp | Greip | Thrym | Thrynga | Tiny | Little Billy | Hrungnir | Red | Tattoo | Gunlod | Suttung | Baugi | Skadi | Hrym | Eggther | Norns
Monsters: Jormungand | Ratatosk | Vedrfolnir | Nidhogg | Fenris Wolf | Lindworm | Wight | Brunnmigi | Siersgrunnr | Garm
Magical Creatures: Dwarf | Elf | Sleipnir | Stanley | Marvin | Otis | Hulder | Nøkks | Vatnavaettir | Nisser | Troll | Raven | Hugin and Munin
Related Content: Rick Riordan | Hotel Valhalla Guide to the Norse Worlds | 9 from the Nine Worlds
Personal Weapons: Riptide | Annabeth's Knife | Backbiter | Frank's Spear | Hazel's Spatha | Katoptris | Nico's Sword | Thalia's Spear | Aegis | Hades' Sword | Kronos' Scythe | Ivlivs | Master Bolt | Poseidon's Trident | Reyna's Spear | Silver Bow | Hades' Staff | Juno's Gladius | Annabeth's Sword | Sumarbrander | Gungnir | Gjallar | Mjolnir | Thor's Staff | Khopesh | Mallory's Serrated Knives | Meg's Twin Imperial Gold siccae blades | Caduceus | Apollo's Golden Bow | Artemis' Knives | Ares' Sword | Ares' Shield | Thyrsus | Hecate's Torches | Minotaur's Axe | Leroy's Sword | Tyson's Javelin | Alex's Garrote Wire | Piper's Sword
Magical Items: Annabeth's Yankees Cap | Helm of Darkness | Keys of Hades | Flying Chariot | Golden Apple | Apples of Immortality | Greek Fire | Hermes' Multivitamins | Leo's Magical Toolbelt | Nectar and Ambrosia | Pandora's Pithos | Winged Shoes | Golden Fleece | Stygian Ice Whistle | Serapis' Staff | Magic 8 Ball | Arrow of Dodona | Pig Ball | Mechanical Spider | Angel Statues | Athena Parthenos | Chiron's Wheelchair | Diocletian's Scepter | Flaming Dodgeball | Gleipnir | Poseidon's Pearls | Queen Hippolyta's Belt | Mistletoe Arrow | Frank's Stick | Expand-o-Duck | Caligula's Caligae | Ran’s Net | Rune Stones | Nábrók
Spoils of War: Minotaur's Horn | Medusa's Head | Kampê's Scimitars | Nemean Lion's Pelt | Gorgon Blood | Cornucopia | Lydian Drakon Hide | Phineas' Robe and Slippers | Triptolemus's Almanac | Odysseus' Astrolabe
Items: Camp Necklace | Chameleon Armor | Daedalus' Laptop | Golden drachma | Denarius | Red Gold | Mark of Athena | Thalia's Shield | Video Shield | Wristwatch Shield | Golden Mango | Sibylline Books | Letter of Recommendation
Ships Amos' Boat | Argo II | CSS Birmingham | Egyptian Queen | Julia Drusilla Yachts | Pax | Queen Anne's Revenge | Reed Boat | Naglfar
Blessed Metals: Adamantine | Celestial Bronze | Imperial Gold | Stygian Iron | Bone Steel