Board Thread:Speculation House/@comment-85.130.101.225-20130816112245/@comment-24198837-20140726201604

Aura only lasts so long; You only have so much. When it's all drained, Remnant people are no different from Earthern people, and just one full-strength strike from any hunter would turn you into paste.

Everyone has an Aura, however, it can be strengthened/you can gain better control over it through training. Thus, it's only viable as a shield/buffer once you've trained for a while.

It's just like in reality, how everyone has muscles that keep us alive, and they never go away - but you need to train them to use them as tools. For example, My arm muscles will always be able to lift my arms up, as they're supposed to. If I want to lift a couch (Doing more than my muscles naturally need to do), I have to train them to do so. Same Idea here. Everyone has an aura, you just have to train to be able to use it as a tool. It doesn't naturally defend you... but it can, if you train.

Pyrrha jump-started Jaune's aura, so to him, it's like he's been training for a while. That's why it activated. With a normal citizen, aura won't stop a death blow automatically. With someone trained, it will.

...or, at least, that's how I've interpreted what we've been told.