[Waedawen]

Like what Ele said, the AC number in your inventory screen is the crutch that you should rely on. Skilling up in Defense, Block, Parry, etc and getting points of Agility influence this number directly, and as such you should make the itemization decisions to make THAT number, AC in your inventory, as high as possible.

I'm sure the block/dodge/parry formulas actually include the hard number for Agility, but I'm very sure that the hard number for AC matters much, much more for every check that occurs on a melee swing.