I have a few ideas. Most of them are for the Dark Knights. Here they come:
1. When the Dark Knights capture a town, you should be able to easily buy black armour from the armour merchant.
2. When they hold a town, you should be able to go to the tavern and recruit Dark Knights from there.
3. The idea of a medieval-aged pistol, which works using gunpowder. To shoot the pistol you've got to have both the pistol and gunpowder in your weapons youre using spaces, like bow and arrow. It's better than a bow but no over gmod because It's an early-aged one.
4. NAVIES AND DOCKS. On coastal settlements, you should be able to build a dock. Once there is a dock built an option will come up in the town/castle interface saying /Build a ship./ and you can build different types of ships, some expensive, some weak, some trading ships. You should also be able to go onto a ship and travel by sea, which gives me the ideas of pirates as the type of bandits on sea.
GTG Now, I have more but I'll post later.