Board Thread:Questions and answers/@comment-27279375-20161007014021/@comment-5028662-20161007165426

Judging by the colour scheme and patterns on the sword, I think it was the Hihiirokane. It has the ability to damage spirits (iirc, Tomonori used it in Phase Shift 1 to wound Terumi), so I'm guessing that had something to do with what happened afterwards.