I think:
Let's move faster. It takes too long to trade and buy gear at different fiefs.
Fuck this all or nothing battle scheme. If timer runs out, let's keep our troops and unspent arms. Let a retreat be a retreat. If you have a bad roster, you retreat but you keep most of your troops and gear. Perhaps 3/4 of your men escape while the remaining quarter have to fight.
Capping the flags is a rout, and the entire army is wiped (as is current). Perhaps it should take 10 minutes to retreat so people don't retreat seconds before the flags are capped.
Give gold rewards for mercs. And make it based on placement. That way top players may fight for the underdog to get more gold. 1st on the losing team pays better than 3rd on the winning team.
Villages, castle and towns are all the same now. Villages should not have garrisons, while castles should not sell or buy. Only cities should be able to do both.
I also think villages should be 'buy fiefs' while cities should be 'sell fiefs'. A person should be able to make money taking stuff from their village to sell in the city. Traders can make more money by selling further away, but this game should not rely on long distance traders for the economy. Actually, owners of villages should get their goods for free and sell to the cities, with surplus going to the town centre where traders can buy it. So, S&D builds up till a lord brings it to the city. He gets his goods for free, while the city owner collects the taxes. Traders can buy at the town centre for a slightly higher than market value and still get the distance bonus, which means more income for the buying town.
Ok, this is getting complex. So I'll stop now. But I have many ideas concerning economy and warfare, but have no idea of what is possible and what isn't. So I'll shut up now.