RWBY - Because the blood that we spilled can never be undone. I'd be lying if I said I didn't have fun, when i saw you fall down on the ground after what you've done to me! Don't expect any sympathy.

…Well the problem with semblance is that it only works as long as you have aura left… So if Jaune already started to take damage from the fire it would mean that his aura is already depleted, which in turn would mean that his semblance ain't worth crap and he end up as a well done steak

This is actually kinda confirmed in manga. That's how the Knight from White Trailer was able to hurt Weiss.

And since manga is “canon untill stated otherwise”, we can assume that’s also true in the show.