Board Thread:Speculation House/@comment-16348034-20130823234203/@comment-3146930-20130823235126

Aura may be different from one person to the next and have different abilities. Lie for example mostly used his as a shield before using it to increase the strength of his strikes. Some have said that Ruby's speed (and the rose petals left behind) are a result of her Aura. I also agree that when Yang goes all crazy and her eyes turn red, this is her Aura. It seems like Yang isn't in control of herself in this state and it could just be she has a hard time controlling her Aura and herself.

Weiss on the other hand is more of a Dust user, so her skill in using Aura may be limited to boosting her Dust-based attacks. Blake so far is the only main character not shown using Dust or Aura (if Ruby's speed is an Aura ability).