Board Thread:Speculation House/@comment-16348034-20130823234203/@comment-3146930-20130824004953

Aura is the manifestation of the soul, so depending on the type of soul you have can result in the type of power you have. Someone who is quiet would have a defensive spirit, maybe even have the ability to make barriers. Someone who is uncontrollable would have a power that reflected that, maybe giving them strength or something. Someone who is energetic could have super speed.

Either way, Pyrrha claimed that you had to practice using it. So it is a skill that one can improve on if they choose. Weiss for example hasn't been shown using Aura, but she is a skilled Dust user. If Ruby's flash-step is her Aura ability, then she may have just enough practice to use it, but relies on her weapon more.