More thinking out loud here, but perhaps the example of the saving throw would be useful here.
i.e.: Your Agility% is your chance to save against Cannot miss attacks, reducing the damage by 1/2.
This would pretty much single-handedly remove Agility's major weakness of not being relevant against a fairly large number of attacks. Indeed, with very high Agility, you would end up dodging a large number of normal attacks and would have nearly assured successful saves against Cannot Miss stuff. Your main weakness would be status effects, but this provides a good contrast with Vitality which (with this change) probably is the less effective of the two at mitigating hits. Vitality also remains the more reliable choice (even with a 50% save you could nailed 6 times in a row, but 50% better HP is always there for you), and the only choice if you want to use Veils (since these don't work if you aren't getting hit
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The check would be unopposed except by the attacker's level, so Cannot Miss attackers still don't need Agility for accuracy themselves. And there would be no further penalty for defenders with crappy Agility, it would just act the way it does now.
Of course, saving throw chances hit 0% if your evasion is disabled in any way (Stun, Paralysis, etc.)
Finally, I could optionally have EVD buffs/debuffs affect the mechanic too, which would give another way (besides status effects like Stun) for Cannot Missers to potentially mitigate enemy saves.
Note however, that you only have a positive bonus for a stat if you are investing *more* than 1 point a level into it. This mechanic would largely only be applicable to characters willing to invest significantly in Agility, it isn't going to act as a blanket nerf/buff across the board.
). They're fine against standard melee brutes but ho diggity their life becomes pain against things that auto-hit.
