Board Thread:Speculation House/@comment-27883360-20160305074527/@comment-24772070-20161211222728

I think it's probably enhanced senses or an extreme amount of aura-related skill. I mean, Fox is the only other person who's been seen to make Grimm explode, and only Ren has been seen to have the ability to detect danger (I would say it may just be a way to detect things you otherwise wouldn't be able to see, but he hadn't noticed Qrow in six months), so I think he just has an enormous level of skill with aura (Remember, Pyrra mentioned that knowing you were being monitored could be an aspect of aura).