Is there some sort of scale that we could compare Magil levels to? Then compare that to the 'cost' of spells. Dunno (its part of the reason i've been hesitant to break out the demon arm. That and drammaaaaaa)
It's... kind of hard?
The only people I have specific stats in regards to that aren't good examples of your standard magi.
The best Asuna wielded a giant anti-magic paper fan for a large chunk of her screentime. >.> <.<
@harinezumikoukenAsuna is one of the blandest characters I have ever read. ^^; Then again I only ever read the first two SAO novels before deciding that it had good concepts and ideas but the execution was... Flawed, basically. ^^;
Also I refer to Kirito as "The Bland Swordsman" so that his title doesn't get mixed up with the true Black Swordsman. :D