[herbert]

Originally Posted by LelouchGeass

Its actually a group of special fighters. The manga kinda clarified Layfon as one of these special people who have tons of power in them.
novel spoiler

Spoiler:

Layfon keeps his strength secret, so its not the weapon, but the person.

Spoiler:

No, the formal title for them is 天剣授受者 which literally means receivers of Heaven Blades. Heaven blades are 12 weapons made of special/mysterious material(白金錬金鋼), so 12 receivers at max (normally they can't find enough members though).