Linchpin Keyblades (RoTs)

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 Road of Twilight series it was confirmed that the χ-Blade was indeed a Linchpin Keyblade and that at least five more similar Keyblades exist out there.

Keyblades and Wielders:

 * χ-Blade - Unnamed Original Wielder, currently destroyed.
 * γ-Blade - Unnamed Original Wielder, currently destroyed.
 * ξ-Blade - Tenno (original body incapacitated, reincarnated), Prince Higeki.
 * τ-Blade - Mahikari (original body incapacitated, reincarnated), Arashi.
 * ϱ-Blade - Mahikari (original body incapacitated, reincarnated), Arashi.
 * ψ-Blade - Master Xehanort (deceased, reincarnated), Xehanort.

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".