The second Loom shouldnt increase Body armor, but reduce weight by, lets say 2.0 Points for medium, 3.0 for heavy and 1.0 for light armor.
That way, Armor bonus will still be ok, and the fact that the ARmors become lighter will be a plus also, but not as big as the additional body armor.
I personally think Loomed armor is okay, but since the topic comes up here and then I decided to introduce you to my idea.