^ Then save and your agility will be 1000 BUT agility also effects how often you get hit so....you probably wont be hit by any enemies if you do this...think of it as God Mode but with a 1 in 1000 chance of being hit.
also search around for "realistic combat" and "oblivion style combat" there are a few mods that give you the behavior you want without having to "cheat" your stats, if you are into caring about such things that is.