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.

Undertone
An aubade is traditionaly a poem or song about two lovers seperating at dawn. This metaphor could be applied to several of Roxas' (platonic) relationships:
 * Roxas recieves his name from Xemnas in Twilight Town, almost completely seperating himself from Sora as he gains his own identity.
 * When he escapes from The World That Never Was, he travels to Twilight Town, severing his ties with Organization XIII, but more importantly Axel.
 * In his last confrontation with Xion at the clock tower in Twilght Town, Roxas defeats her. Although confronted, this is still the only time where Roxas has a direct effect in seperating from someone he still cared for and who cared for him as well.
 * Roxas' residence during Sora's final stages of memory recovery is a simulated Twilight Town, where he stayed until he was fully assimilated into Sora, ultimately ending all relationships Roxas had formed beforehand.

It should be noted that dawn leads to twilight, where as the weapon Aubade can, where available, lead to Twilght Town, where these events take place.

Trivia
The original Japanese name, Aubade Lord insinuates that Roxas is the "Lord" of aubades.

It is safe to assume that the metaphors do not apply to Xion, seeing as how she was merely a copy of Roxas.

Most of Roxas' weapon names refer to guilt/pain or the night; Aubade is the only to do both at once.