[Butz]

Since an aura is somewhat a constant effect however, it might be considered that in addition to providing bonuses and dealing damage per second, it should also drain grace per second. Casting once would activate the Aura effect, Casting a second time would deactivate.
Similar to summon spells, grace would not regenerate while Auras are active. (To prevent endless auras.)
Though grace is allowed to go into the negative areas. Auras should probably stop when grace reaches 0.

Otherwise, it sounds much better than the current Auras.
Perhaps aside from elemental auras, you could also have Healing Auras, and such.