Board Thread:Speculation House/@comment-27404492-20170511131216/@comment-26397825-20170613191239

I always though Emerald took out most of Vovo's aura because she struck hard in a vulnerable spot that likely would have been lethal if Coco didn't have aura - such as the junction between the shoulder and neck.

It's not DnD rules, it's just hitting a naturally weaker part of the body hard because you have time to wind up the hit and put more strength into it due to your opponent being distracted. More aura is required to keep it from breaking through, and if she gets hit hard enough the pain will make her vision go spotty at the very least, which then gives Emerald time to follow up with the hit that launched Coco across the arena.