Board Thread:Speculation House/@comment-24718692-20140322030224/@comment-28277272-20140404232134

Considering Pyrrha told Jaune he has a lot of aura, I presume some people have less aura than others, and it's highly possible Weiss isn't the best blessed regarding auras (I mean, if she had a lot of aura and could control it perfectly, she would be too powerful, she needs to lack something). On the other hand, Pyrrha is introduced as one of the best students (well, we can assume so since she won the Mistral tournament four times in a row and graduated top of her class), so maybe she has reached a level Weiss hasn't yet. My point is, the gap between their aura might be huge, which would explain why Pyrrha can use aura without her weapon but Weiss can't.