Board Thread:General Discussion/@comment-3003995-20141017010235/@comment-5398287-20141017012021

Doubtful. He forged it himself, and it apparently has the name of "Sayabuse" or something. Plus, Ryujin Jakka has an actual sheath, and its sealed form was nowhere near this powerful.

He was thanking Yhwach not because the latter let the blade come into existence, but because Yhwach's arrival gives him an excuse to use it in battle.