Thought that I answered this in another thread. Aha! I did (and it was in answer to things you asked, no less -- hehe), and here is what I said -- I highlighted the important part.
The AR is assigned to the piece of armor that covers the chest/abdomen/groin areas. Other pieces of armor add to the total DB of the character. This makes a full suit of plate armor be AR 10 and have a base DB of 30 (IIRC). To this, you add your quickness bonus (adjusted by the maneuver penalty) and any other factors.
So, to reiterate, the maneuver penalty for the armor counts against the quickness bonus. However, like in the core rules, the maneuver penalty will not reduce the quickness bonus to below zero.
In other words, the maneuver penalty is also the quickness penalty when it comes to figuring actual DB. However, this is offset some by the fact that tougher armors do increase DB as well.
