Board Thread:General Discussion/@comment-37541747-20200204005908/@comment-4010415-20200204021621

Um... Ruby and Weiss were literally displayed to have lost Aura from using their Semblances in episode 3 of this very volume.

When Team RWBY land at the abandoned Dust mine, Blake checks their Aura levels on her Scroll. Yang lost Aura, presumably due to taking damage from stopping her fall abruptly with gunshot recoil, but Ruby and Weiss landed safely by using their Semblances and still lost Aura. Blake, meanwhile, landed safely without using her Semblance and was shown to have 100% Aura.

The thing is, Ruby using her Semblance only reduced her Aura level to 98%, and Weiss using glyphs and a partial summon only reduced her Aura level to 96%. It's such a minute amount that it doesn't make a huge difference, and we have the fact that people can regenerate Aura, so as long as they don't spam their Semblance, they're fine.

Though, of course, you have to take into account that this is displaying percentage and not actual total units, and some people have more Aura than others. 2% for Jaune is a larger amount than 2% for Ruby, for example.

There is also the fact that, all the way back in Volume 3, the Aura level screen shows that Emerald lost 5% of her Aura despite taking absolutely zero hits. This was after she used her Semblance to make Coco hallucinate Yatsuhashi.

So, um... yeah, they have actually shown people losing Aura from using their Semblances. It's just not inherently obvious because we can't see them actively losing Aura unless the camera is looking at a TV or Scroll that's literally saying "Hey, this person lost Aura."