You know that the riding skill improves the base stats or whatever of your horse.
So actually, the "effective" maneuver of the arabian warhorse, with 7 riding skills, is really out of the world.
If you give it more hp, more armor, more speed, then it will fear no range (easy to avoid, and easy to quickly get in killing range) and other cavs (easu tou outmaneuver, and can even outspeed them) while also being way harder to kill ?
One thing the 7 riding skills requirement did, was actually make the cav realised how much benefit they have when upping this riding skill. Not specially a burden.
It's not cause it has high requiring skills that it has to be "unstoppable", else you'll soon see 2h (*cough* leshma *cough*) asking for a 21 str requirement sword with as much speed as the katana, but with 45 swing cut damage... or archer asking for a 8 PD bow with the same speed as the rus bow, and 5 more missile speed and damage than the longbow...
I wouldn't mind if it gets +5 health. But that's really all. You can't have the most maneuvrable horse, and with high survivability and high charge damage.