Armor rating might improve on each single armor piece individually. 10% more on 8 armor is 8.8 rounded down to 8. Put in another point into the armor perk, if you still see no change, it must be a bug.wondering this myself. Wearing a mix of iron and steel armor with a total armor rating of 37. Decided to start buying the heavy armor perks and at level 1 your supposed to get a 10% boost to armor rating but when checking it still shows a rating of 37 instead of the expected 40 (or 41 if rounding).