One-Winged Angel

The One-Winged Angel (片翼の天使) is a form of Sora's Keyblade. It is obtained by defeating Sephiroth at the Olympus Coliseum in Kingdom Hearts: Final Mix. It is also available in Kingdom Hearts: Chain of Memories, along with the other Final Mix "bonus blade", Diamond Dust.

Appearance
The One Winged Angel resembles Sephiroth's Masamune sword, although its handle and blade differ, in keeping with the design of a keyblade. Its keychain is in the shape of a wing, hence its name, and the end of the blade bears a resemblance to the spell Meteor, which was a major plot device in Final Fantasy VII, the game that originally featured Sephiroth.

In battle, the Keyblade becomes completely engulfed in flames when it is swung. This may be a reference to the Nibelheim Incident seen in the Compilation of Final Fantasy VII, in which Sephiroth razed a village to the ground.

Etymology
One-Winged Angel is named after the famous battle music played when fighting Sephiroth in the Kingdom Hearts series and the Compilation of Final Fantasy VII. The name 'One-Winged Angel' refers to his Safer form from Final Fantasy VII. Despite resembling a Seraph, a six-winged angel, the title refers to the multi-colored wing that replaces his entire right arm. Since then, in almost all of Sephiroth's appearances he has been seen with one large black wing on his right side.