My apologies, it's now 4am and my reading comprehension/overall language skills are dwindling.
My thoughts were along these lines:
Attackers get a fair but small percentage of weapons and armor recovered on a successful attack, no resources; they are traveling, not condusive to hauling wood & iron.
Successful defense against an attack rewards you with recovered weapons, armor, and the bonus of wood/iron recovered from damaged weapons/armor to use to either make more weapons of war, or sink into buildings.