Then I suggest rewatch volume 5 and onwards because it shows, even in the battle in Mistral, Yang kept her cool the entire time and never showed her semblance. The only times she got angry in volume 5 was: Blake being mentioned (emotional pain), at Ozpin, and her rant at Raven. Volume 6 she was barley angry though only angry at Ozpin for his lies. Then onwards she rarely even got angry in volume 7 and 8.