Aubade

The Aubade (オウバードロード) is a form of the Kingdom Key that appears in Kingdom Hearts 358/2 Days. It is one of two unique weapons that Roxas and Xion can wield.

The Kingdom Key is changed into the Aubade when the Mystery Gear is equipped.

Etymology
An "Aubade" is a song or poem evoking dawn which is traditionally a love song of two lovers parting in the morning. While not fully romantic in nature, the most defining aspects of Roxas's personality occur in Twilight Town: after leaving the Organization (and specifically Axel), he travels to Twilight Town; there, he encounters and is forced to defeat his close friend Xion, destroying her and giving up even his memories of her.

Trivia

 * The names of Roxas's weapons generally refer to either the pain of parting and loneliness, or light phenomena. The Aubade is the only weapon to do both.