Obsidian Flute The flute allows the user to control (alien) creatures, the mutated crocodile personally created by Five for example.

Leather Sleeve A leather sleeve with a one foot long blade that retracts from the underside of his wrist. John takes it after Five knocks himself out in Fall of Five

Prism Mentioned, but nothing specifically known about it. Five claims that it can undo effects of certain things, like his Externa, and suggests the use it on Ella and John.