User blog comment:WeissSchnee/RWBY Intro/@comment-74.88.211.31-20130707083705/@comment-11481298-20130707091458

If that's the case, then maybe. Weiss seemed to be an important case, and since there's no other instance of blood anywhere, I guess it's safe to say that it'd only show up when it's as important.

So, if any, very little. But that's just a guess.