Fenrir

Fenrir is a keychain for of Sora's Keyblade.

After defeating Sephiroth in the Radiant Garden, Sora witnesses a battle between Cloud, Sephiroth, and Tifa. After Sephiroth and Cloud fly away into a duel, Tifa thanks Sora for his help and gives him the Fenrir keychain. It is the KHII equivalent of the Metal Chocobo

The Fenrir Keyblade takes on the appearance of a pin tumbler lock key, with bandages adorning the handle. It is one of the longer Keyblades.

Despite the passive ability of Negative Combo, the Fenrir Keyblade makes it up for its high attack power. It is also considered to be the strongest Keyblade available, second only to Ultima.

Fenrir is the only weapon with the ability "Negative Combo." Combining Fenrir with Sora's "Negative Combo" ability is the only way to allow Sora to unleash a finishing move each time the attack command is executed. This is especially useful for the Twilight Town minigame in which Sora (or Roxas) uses the keyblade to destroy piles of junk.

Background
Fenrir is named after the motorcycle ridden by Cloud in Final Fantasy VII Advent Children, which is in turn named after the wolf-son of the Norse god, Loki. Fenrir has also appeared as a summon in multiple Final Fantasy games.