I have a build in progress that is level 11. My current Dexterity is 21 with feats and equipment. I am using a +5 Mithril Chain Shirt, which is Max Dex 6, and a +5 Mithril Tower Shield which is Max Dex of 4. As I understand things, if I take Fighter Tower Shield Mastery 1, my AC should go up by 1. Once I get to dex 22 and take Tower Shield Mastery II, it should go up by another 2, 1 for filling our the mithril chain shirt, and another for filling out the TSM. However, when I took TSM I, my AC did not appear to change.
Does anyone know if this is one of those display bugs, or is it broken at the moment? I suppose that a third option is that I'm just confused and wasn't looking at things the right way...