It might not work on horseback, or it might be only the over head attack. I mean AFAIK it's only the overhead on foot that CTB.
I want to say, if you're interested in power leveling combat skills in a new game you can use friendly fire against an allied party to easily raise up bow(or other ranged), riding and at a slower rate athletics. Just attack looters near any party and they will attack too, then at battle end when they just cheering, shoot everyone in the face, save archers for when you need refills, dismount to get athletics instead of riding. It's pretty boring and totally an exploit (that needs to be patched) but for the last 8 months this is a fast way to power level these skills. I will say also, gaining melee combat skills it not important at all in anyway. You starter char with zero skill is perfectly competent with all melee weapons. Bow on the other hand.... getting up to 150+ fast is certainly useful.
if you level athletics enough it's easy to kill all of them alone (any bandit camp final boss). As long as I can move fast enough to fight grps, blocking and hitting becomes a walk in the park. There's a reason why I find M&B combat to be boring, although in BL it's improved a bit. (I only get wrecked when momentum glitches on me)
That's medicine skill(from own troops), not riding, bow and athletics from allied FF.
