do 18/18 or 21/15, 4 shield skill, max ATH, PS, Riding, use 3 WM, 110 1hand wpf 80-90 polearm wpf, rest (3-5) in IF
there, you have a great lancer/1hand cav build that is just as strong of a sword and boarder/hoplite/whatever polearm you want build in melee. Melee cav and melee infantry is more fun, imo, then ranged classes.
Xbow cav is kind of hilarious, but unless you are already a skilled horseman and have good decision making you will be relegated to shooting a few horses here and there until you get wrecked by lancer cav or enemy ranged. I think being a better horseman (you get good awareness fast from melee cav) would make you enjoy ranged cav more on your next generation. Your score as melee cav is almost guaranteed to be much better as well, and the speed bonus makes even non loomed melee weapons hit very hard on horseback. Non loomed bows and bolts are fairly weak when mounted.
If you want to hybrid 1hand and xbow cav together, you will need to sacrifice bringing a shield to bring more ammo and be lighter on iron flesh and stuff. You could still just do 18/18, max Riding, Athletics, HA (you get 3 at 18 agi), WM, and Powerstrike. This gives you 2 left over, either for shield or IF. You could have 130 xbow wpf and 105 1hand wpf with this build easily.