Sumarbrander

''This article is about the sword. You may be looking for the book.''

"Dude, blades before babes, you know what I am saying ?"

- Sumarbrander to Frey

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 its master.

History
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 he was found and renewed by Magnus Chase. Sumarbrander ended up being betrayed by its original master, although he continued to obey Skirnir. Sumarbrander (Jack) is one of the most famous swords in Norse Mythology.

The Sword of Summer
Magnus 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, 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 Junior, Magnus pulls out Sumarbrander, who ends up having 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 touches him too soon the demigod could pass out or die.

He was then used to track down Thor. When Magnus and Sam get Gerriod'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 new rope to Jack to tie up the wolf. Magnus then uses Jack to heal Halfborn Gunderson.

When he and Magnus are greeted by Frey, he desperately tries to attack the lord of Alfheim while Magnus restraints him. He helps interrogate Andvari and picks up the cursed ring before tossing it to Magnus.

The Hammer of Thor
Magnus call on Jack when Otis was 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 the assassin's 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 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 is time for battle practice. Magnus was surprised to learn that the two of them hung out the night before, he skipped out on battle practice due to a date with a polearm. After dinner, he helped Magnus catch up to Sam and he interrupts their conversation.

He is summoned in a wights tomb to see if Mjolnir was in an iron coffin. He eggerly asked if he could open it. When he learns that the sword Skofnung was inside the tomb he became excited. 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 Hearth 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's 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 does not fight 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. He is upset when Percy sheaves Riptide and turns back into a pendent. He is summoned again when a wolf is trying to break into the Chase Mansion, he is upset that he was not needed.

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

During the voyage he and Magnus spare 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.

Appearance
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 counterweigh 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.

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

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

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

It 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 it is a "weapon that wasn't designed to be a weapon, a sword that is best used if you let go meaning it 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.

Etymology
The sword's Old Norse name means "Summer Sword".

Trivia

 * When wanting to be named, it mentions that it never liked the name Sumarbrander because it was so long.
 * After Sumarbrander begins to speak in The Sword of Summer, its 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 when he was a demigod, indicating the Norse gods are older then the Norse themselves.
 * Jack is a paradox, being a "weapon that wasn't meant to be a weapon" and a "sword best used by letting go".