I think it might be cool if after every battle, you could send caravans or a new gathering unit to loot the armor or weapons off slain units. Since so much of it would be damaged, they can only gather 20% of the advanced resources that the troops cost was. This would allow much quicker growth of the military, but you would still need to maintain your city, otherwise you won't be able to support your army.
I don't really see that many armies for just attacking, I only see raiding, defending, and sieging. That may be because I am relatively new here, but it seems to me that this would bring some purpose to making an attacking army.
People might now try to attack other armies purely to loot the equipment off of them. I think a reasonable counter would be that you cannot loot archers or spearmen. This way, you could still defend your city, and send your army away where it cannot be hit when you cannot dodge.
For those of you who have played ogame or something similar, I am trying to suggest a less hardcore version of fleetcrashing so the game can keep it's slower pace while newer people can still catch up. Any thought/adjustments?