A little bit of clarification on the nature of Roukanken and Hakurouken:

Roukanken is a phantom-slaying blade that can cut and kill even things that are totally intangible because it was forged by youkai smiths to be [i]so ridiculously sharp[/i]. Its supernatural sharpness lets her do things like cut lasers and all kinds of crazy stuff.

Hakurouken's a bit... weirder. It doesn't kill, but it can cut things with no physical presence, like confusion, and can hurt things by "attacking" the soul. But the "attack" on the soul isn't really understood unless you see it on a purely spiritual existence. Hakurouken actually instantly causes a spirit to reach a state similar to Nirvana and vanish.

[@Rin]: ... In that case yeah it should probably be pretty dangerous to him. ^^;