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

The main problem is we already know that Grimm can get past a person's Aura. In fact anything that is sharp enough is able to get past Aura, as it works more as a buffer and not a 100% defend all shield. This can be shown when the Ursa manage to cut a few strands of Yang's hair. Jaune also has a bruise from Cardin punching him despite still having some Aura left when he was fighting the Ursa Major. The claws, stingers, feathers, teeth, ect of the Grimm could most likely get past Aura with little trouble, which is why anyone in their right mind would try to avoid injury.