Keyblades in Kingdom Hearts

Powers

"The Keyblade. A truly marvelous weapon...were it only in more capable hands."

—Xemnas during first Hollow Bastion visit in Kingdom Hearts II

As the name implies, in combat, Keyblades are used in a manner similar to swords. Despite the fact that most possess no actual blade, Keyblades still make efficient combat weapons and are shown to be particularly effective weapons against both Heartless and Nobodies. Keyblades can vary in appearance by placing different keychains on them. However, there are many Keyblades that do not possess a keychain, possibly to represent the realm they came from, or how they were made.

Most Keyblade wielders are also able to extend their Keyblade's length with Light or Darkness for their ultimate attacks. This has been seen for Sora's Ars Arcanum, Roxas, Xion and Riku's Limit in Kingdom Hearts 358/2 Days, Sora and Riku's Limit, Eternal Session, and Terra and Aqua's Mode Change, Blade Charge.

The main power of the Keyblade, however, is the ability to seal or open the barriers between worlds, as well as "lock" a world's Keyhole, preventing the Heartless from attacking that world's heart. As an offset of this ability, the Keyblade can also be used to lock or unlock any lock, allowing the user to access any sealed interior, whether it be a locked room, gate, or treasure chest.

In addition to its base powers, it is possible to modify a Keyblade's appearance and powers by attaching various Keychains or Gears in the wielder's inventory. There are other instances of the Keyblade changing form, such as when Riku's Soul Eater becomes the Way to the Dawn and when Roxas's two Kingdom Keys transmute into the Oathkeeper and Oblivion, but the mechanism behind these transformations is uncertain.

[edit]Inheritance Requirement

The Keyblade has a special power that only lets a chosen wielder hold it. This is proven when Sora gives his Keyblade to Jack Sparrow only to have it come back to his hand. In the final battle with Xemnas Sora was able to hold Riku's Keyblade and the same goes for Riku and Sora's Keyblade.

While there are many qualities a Keyblade wielder must have, the only known requirement is that they have an exceptionally strong heart. There are some instances where if one has an exceptionally strong connection to someone who can wield a Keyblade, they will be able to wield a Keyblade.

It is implied in Kingdom Hearts Birth by Sleep that it is possible for a Keyblade wielder to choose a person as his successor if they have the main qualities that allow them to hold a Keyblade, as Terra chose Riku to be his successor. Kairi seems to have inherited the same ability when she accidentally touched Aqua's Keyblade. Aqua originally considered choosing Sora to be her successor, but decided against it because Terra had chosen Riku and she did not want the two to fight all the time. However, Sora nonetheless gained the ability to use the Keyblade when Ventus' disembodied heart fused with his own.