>>149683069
the sword is not sentient however it was made with the specific purpose of sealing a demon's heart and as such the hilt and scabbard are representative of Assiah(our world) and Gehenha(demon world/afterlife), the blade is essentially less important than those parts. So when he "lost his confidence" with regards to his power which it's directly tied to the sword it was almost as if the seal that was destroyed the night Satan reappeared was made back in tact, not completely but enough that the tool meant to harness it was rendered useless