Siege nexus.

Catapaults, battering rams, ballistas, wooden and stone walls, ramparts, and walkways... pennants/flags/banners, arms and armor (armor accessories? why are there no breast plates???), medieval home supplies, shop inventory items, you name it... tons of possible items that would fit the game and still be unique enough to warrant new designs.

I'd dig up a list of hundreds of ideas from a similar (old) thread but I'm lazy.