What would you say Aura would grant as a mechanical benefit? Extra AC? Temp HP? A plus to certain modifiers? What would you count a Semblance as? Would it be an SLA or something else?
Aura would be slowly regenerating, provided by a template which also boosted all physical stats a certain amount, probably increasing based on HD in all respects. Likely, it would translate your current health pool into a Gamer like system, turning all incoming damage nonlethal and healing it. When it broke, you would start taking damage to your regular health pool, and also probably gain Fatigued status effects.
RWBY shows semblances (if not physical benefits, and even then who can really say, most fights are over soon after that point) are still accessible even with a broken Aura, so I'd say it provides a steady stream of power but you can't spam it if fatigued... something magic can help bypass.|
Overall, I can't say how this would be particularly balanced stacked on top of the D&D system. If I was making a RWBY quest with 3.5/Pathfinder rules, I would say Aura forcefield basically
was your pool of HP, in addition to what the template provides, and that overall the human body is hilariously fragile without it, which would line up with the show and either -10 to death or -25% total HP per DP's house ruling about downed characters.
Me and TNE discussed it briefly in the past.
If I had to say what would happen if Richard awakened his Aura, and I'm not sure if it's even a thing he could do (he's got his own metaphysical weirdness happening with him), it would probably be a really flat and underwhelming boost in power. For a Level 5 character, +6 to Strength, Dexterity and Constitution is a big deal, but it hardly makes a difference for a Level 20 Martial Initiator who needs CR 20+ Psionic Illithid Cerebramancers to vaguely pose a threat to him, or something like a Great Wyrm in melee range with feat selections optimized for rip-and-tear (like Amrelath).
Except for the Semblance, which would, given his personality, be very straight forward, and
very fucking lethal.