Percy > Athos
Alot of mages in the DL have things they can do besides cast spells. Many of them have physical attacks, however weak. Some of them have secondary skills they can use. Fire Emblem mages, however, do not. No physical attacks, no skillsets at all. Nothing but magic.
So what is the most powerful FE mage, the legendary Archsage Athos, to do when confronted with Silent Lake?
Whatever the actual answer to that question, no one expected him to smash his Forblaze tome into Percival's face hard enough to break the knight's nose.
This action ultimately didn't do him any good, of course. Percival still managed to get over his surprise and easily dispatch the old sage with his superior physical prowess. And even if the knight somehow lost that scrap, Athos would have been disqualified for using a physical attack he's not supposed to have.
Still, losing the match or no, it'll be some time before any young whippersnappers go traipsing around on Athos's lawn after that little display...