Bit late to this, but this is like putting up one of Chase's scores up and saying his current class is OP.
Zero_SAT is one of the best HA's, no question about it. I'm not saying there isn't a problem, but the OP's screenshot is misleading.
Your typical HA doesn't have a score anywhere near that.
HA dmg is not the problem, the ability to kite endlessly is. (Bodkins are a bit of an issue though)
Typical HA build's have atleast 6+ riding minimum, usually 7 and above. (I personally have 8)
The only way other cav can catch me, is if I let them (or make a mistake).
Either there needs to be some widely available range weapon, capable of taking down or detering HA/HX.
Or, there needs to be a nerf in HA/HX riding.
A possible solution:
Make the HA skill give less and make it every 3 agi, therefore requiring more skill points.
e.g. 4 would now be 6-8 for the same ability.
Though this would obviously need tweaking.
Another solution:
As already mentioned, HA skill reducing the riding skill.
Every 2 points in HA could reduce riding by 1.
.. as the voting on this thread shows, it ruins the experience for the rest of the player base.
You would get a similar response for archery/2h or stabby polearms...
It's a leading question.