troops based off numbers of fiefs ...
as of current you have prosperity points you can put into fiefs, either upgrading equipment or increasing their S&D.
Why not make it so that troops are automatically recruited from fiefs at a certain rate which can be upgraded with prosperity points (therefore making you choose a balance between equipment, gold and troops)?
How would factions without a fief make troops?
Edit: How about PP points needed to maintain an garrison. Like increase prosperity, you can increase the maximum army/pop size a fief can hold. Therefore to have 1000's of troops in a fief you will have needed to spend a lot of PP on being able to do that, reduces the amount of PP available to produce weapons and armor. This would make factions have to compromise between large garrisons and cheap/good armor.
Combined with the idea of a different amount of PP required to loom and discount low level items compared to high level items, this would allow you to have a large garrison with poor weapons and armor or a small garrison with high end armor and weapons.
When large factions go to war they can take out their weapons/armor producing fiefs. Leaving their enemy with lots of troops but limited gear. Makes war a lot more tactful and realistic.. Wars have always been focused on cutting of the enemies supplies not just an endless grind of troops.