Linchpin Keyblade (KH3 Duo)

A Linchpin Keyblade is an extremely unique and powerful Keyblade that was designed for special access to all the Universe but more importantly, access to Kingdom Hearts itself, in the Kingdom Hearts III Duology it was confirmed that the X-Blade was indeed a Linchpin Keyblade and that three more similar Keyblades exist out there.

Keyblades and Wielders:

 * X-Blade - Unnamed Keyblade Wielders (deceased), currently destroyed.
 * X-Blade replica - Vanitas (possibly deceased), currently destroyed.

Trivia

 * A "Linchpin" is a "locking pin inserted in the end of a shaft, as in an axle, to prevent a wheel from slipping off" or a "central cohesive element".