Keyblade

As the name implies, in combat, Keyblades are used in a manner similar to swords. Despite the fact that most possess no actual cutting edge, Keyblades still make efficient combat weapons, and are particularly effective weapons against Heartless. However, as a downside to this, the Heartless use the Keyblade as a homing beacon, and thus Keyblade wielders are at constant risk of Heartless attacks at any time.

The main power of the Keyblade, however, is the ability to seal or open the barriers between worlds, as well as to "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. The Keyblade opens and shuts locks by emitting a bright, thin beam of light.

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.

The Keyblade has a special power that only lets a chosen wielder hold it. While there are many qualities a Keyblade wielder must have, the only known requirement is that they have an exceptionally strong heart.

It is possible for a Keyblade Master to choose a person as their successor if they have the main qualities that allow them to hold a Keyblade.

For the sake of this game, it also has the ability to 'Unlock' or 'Lock' a World Shard, and bind it to a location. Meaning that Keyblade Wielders can effectively change some parts of the layout of the grid... assuming they don't get conned into doing so - or lose the World Shard on the way.