Heroes who are weapons or can turn into living weapons for other heroes to wield. Yukine, Soul Eater Evans, and Susanoo are all perfect examples of this. They are a staple in fictional works ranging from fantasy to sci-fi and even theoretical science. They vary in true sentience as well but must function with self-awareness beyond Artificial Intelligence and/or Golems though they may overlap.

Also, to keep this somewhat separate from A.I.s limit characters to those labeled weapons or with Military connections.