Like someone who is not the unbelievably injured guy, the student council member or the nerd who's formidable with a god damned sheet of paper?

I don't know about Rean's speed or reflexes. If we had an indication that some sort of actual bear was involved I'd shrug and say maybe Mitsuko, but if it was Mitsuko I suspect we'd have a lot less Sting lying around to examine.

But while Merciless' aren't superhuman, she's a trained killer and those sorts of things are listed as being exceptional on her profile.