pretty nice suggestions over there, but one of them i have a better idea than it but i forgot, let me check
EDIT: AHA,
keep riding skill, BUT allow player to ride any horse, but make a chance to fall from horse when you get damage, or horse gets out of control when it gets damage, a small chance. higher riding skill = less chance..
and those extra troops, they should only be given to lords of the kingdom, they shouldnt be upgraded from te recruits, just to give lords a bit more taste.