Board Thread:General Discussion/@comment-24155619-20140711014702/@comment-4010415-20140713044121

I always figured that not everyone can use aura to heal, since we saw Jaune's cut heal right before Pyrrha noted "You have a lot of it." I figured that means having a lot of aura gives an added bonus of quick regeneration. Perhaps Weiss has a lower amount of aura. Also, I think the worse a wound is, the harder it is for aura to heal it, and the worse that someone is hit, the harder it is for the aura to protect against it.

For all we know, Weiss got punched in the face so hard that it would've smashed a normal person's skull in our world, and her aura absorbed the majority of the blow, but not all of it.