Don't forget that 2hand cav, while being much more difficult to use, also gets a 25% (or more, I forget) penalty while being used on horseback, because of ~reasons.~
1hand cav, gets no such penalty. So basically the Arabian Cavalry Sword is more powerful than any 2hand weapon in the game on horseback. For no reason.
And there is no damage penalty for using 2hand weapons on horseback with a shield because they are already penalized merely for being a 2hander.
So basically, there is no reason at all to be anything but 1hand cavalry.
I'm an experienced cavalry player and 1hand cav is incredibly easy and does way more damage than any other cav class, with all the bullshit that shield gets you. Its definitely stupid, but using a +3 Lance feels just as/sometimes more OP, since it hasn't been nerfed to shit like the Heavy Lance, and it racks up kills fast.
2hand cavalry is the least effective and most frustrating to play, since it has nothing but downsides compared to the other cav classes.