Perhaps this has been brought up before, sorry if it has. I combined the shields to make supreme shelter and find that it doesn't give any armor class bonus, it does however give the other resistences listed.
I removed all the armor from my fighter and put that shield on with no difference in armor class, thinking there might be an armor class limitation but that wasn't it.
By the way, this mod is a tough mod. I find at many times its an all or nothing thing. Either I beat the monsters or they kill my main character (and entire party for that matter) and there is no escape, hence no going back and getting other characters. I could probably manage an escape now but at the lower level there was no way. Those suckers just zeroed in on the main character.
Thanks,
Romulas