Maybe u could use something like this
Militia Training barracks +1 morale +1 discipline
County Training camps +2 morale +2 discipline +1 weapon
State training camp +3 morale +3 discipline +2 weapon

& for some factions like say the English(who use a lot of non national troops) maybe they could launch recruitment drives in places like Ireland, Scotland & Wales. Kinda like a crusade where u pay a once off fee & get a troop lineup generated by the game. They just build the recruitment centre(chapter house) & can then begin recruitment say 2-3 years they get the troops. It might have to be limited to only one recruitment drve at a time & only 1 every 10 years or something