you can't raise your own agility cause you won't dodge when you attack yourselves. If you get blinded and attack yourself you'll notice you'll hit them all even though you can't hit the enemy very well. The manual says that you only have to be targeted for agility to rise, but that is a dirty lie you only have to successfully evade.

It's kind of a good thing because else if you raised your agility to fast and not your stam/hp, then you would end up with a character that usually dodged everything but then got kod by a single attack when the enemy got lucky. This way you can still level up HP by self flagellation.