User blog comment:Thesupremejoyner98/Grimm that can cut through aura/@comment-3146930-20150113222323/@comment-25857155-20150114035753

I don't think someone's Aura would protect their hairdo from being cut, otherwise it would be nearly impossible to get a haircut. Hair is dead past the root, after all, so why would it need protecting? That's the best explanation I can think of for Yang's hair being cut or ripped out/off at various points.

I think "little trouble" is a bit of an understatement, depending on each individual's Aura and their control over it. Recall, Lie Ren was able to focus his Aura and block the King Taijuto's fangs with his bare hands. Jaune had no experience with Aura prior to Beacon, which is how I would explain his persistent injuries.

Yes, one's Aura can be drained and possibly broken, but an attack would have to have a lot of power behind it to do that in one shot. I'm talking like, an execution shot/throat cut assassination, or maybe a rail gun on the level of Penny's laser. Not even the machine in the Black trailer did enough damage to break Adam or Blake's Aura in one hit, right?