Leviathan

The Leviathan (リヴァイアサン) is a form of Roxas's Kingdom Key which appears in Kingdom Hearts 358/2 Days. It can be upgraded to the Leviathan+. This Keyblade can be a great weapon for combos, as all of its abilities add to combos.

Trivia
During 358/2 Days 's development, the Keyblade was to take an aerial attack-oriented form known as the "Wind Maker" (ウィンドメイカー) when the Wing Gear (ウィングギア) was equipped. Both the Keyblade and Gear were ultimately cut and the Wind Maker's appearance given to Leviathan.