User blog comment:Darkcloud1111/Good Idea, Bad Idea-Best Day Ever/@comment-3257939-20140726015807/@comment-2006510-20140726022548

In Jaune's defense, while he may have a lot of Aura, he's still very inexperienced with USING it

And I believe the same general thing happens with Aura; there are moments where the characters use it (to channel it through the food, possibly), and to block some hits, but they can still be surprised. For instance, when Weiss was slammed into the pillar, she could have been surprised and not instinctively used her Aura to block the damage, hence temporary unconsciousness

Either way, it's a highly in-the-background thing that we can't directly see