I know what Aura does to your side... but...
What about monsters? Like that soldier in the desert prison: he casts Aura on his robots, but I don't see any difference in the way they attack.
Also, I've cast Aura accidentaly (and on purpose) on monsters...
And in Seifer battles, would it make him use Demon Slice/Bloodfest more often?
...I wonder if there are any other magic mysteries out there...