|“||... The hero's soul, cursed blade shall reap...||”|
–The Great Prophecy referring to Annabeth's knife
Annabeth's Knife was Annabeth Chase's primary weapon, and she was very skilled in using it. She used it very frequently, as it was a gift from Luke Castellan (who got it from Halcyon Green, who got it from a young girl) when she was seven. This knife is made out of celestial bronze which makes it a weapon for monster killing.
Originally, the knife or "dagger" belonged to a young girl who was saved from dying in an accident by Hal. She gave him the dagger as thanks for saving her life. According to her, this dagger will always protect the person wielding it. This, however, has yet to be confirmed.
Hal kept the dagger during his punishment in his childhood home, brought upon him by his father Apollo, until the arrival of Luke and Thalia Grace. He gives the dagger to Luke after they come up with a way to escape the mansion, then Hal sacrifices himself to save them.
After meeting Annabeth, Luke replaces the hammer she was using with the dagger/knife he had received from Hal. Annabeth was only seven years old at the time, while Luke was fourteen and Thalia was twelve. Luke makes a promise to Annabeth that he would be there for her when he gave her the Knife so that she could defend herself from monsters that were chasing them. It is her weapon of choice because when Luke gave it to her, he told her that only the fastest and cleverest of warriors could wield the weapon.
Annabeth is very skilled with the knife, although she has been trained to wield a sword as well. After Luke betrays her and joined Kronos at the end of The Lightning Thief, it became cursed because of his broken promise.
Ultimately, Percy's choice to give the knife to Luke is the great choice that he has to make and, since it is the "cursed blade" of the Great Prophecy, Luke uses it to kill himself with in The Last Olympian. He does this by stabbing himself in his Achilles' heel (which was under his left arm), in order to destroy Kronos' spirit in his body so that Olympus could survive and that the Western Civilization could live on.
Annabeth leaves the knife on the Argo II, while she goes to New Rome. When they leave New Rome and set off to Charleston Harbor, Annabeth goes to the Battery with Piper McLean and Hazel Levesque, where they meet Aphrodite. When Octavian and the Romans attack, she tosses it into the water, to send out a signal to Percy so that he could help them. Octavian then complains, "That could've been evidence. Or spoils of war!". She also uses it to shatter the sacred cavern of Mithras and later it is dropped into Tartarus along with Daedalus' Laptop.
Having lost her knife, Annabeth frequently feels sad. She nearly faints when she realizes how long she has had it for. She eventually gets it replaced with a Drakon Bone Sword.
Annabeth gets her dagger back, when she instinctively goes to grab her dagger, but grabs Sadie's wand, from the Kane Chronicles. Annabeth cannot let go of the wand, and it transforms into her dagger. She uses it to fight with success.
- According to the young girl who originally owned it, the dagger will always protect the person wielding it. This, however, has yet to be confirmed. This is possibly true, because Annabeth only got severely hurt when she fought with her sword, in The Blood of Olympus