Good idea. Balanced. Well thought out solid suggestion. Hopefully I can see more of your posts in the future.
I'll agree with you, because my friend Uumdi will go from 20-4 as a 2h on horseback to 30-3 if they could put in your changes.
Going to repeat what as said earlier, it is not a linear 30% decrease. It isn't very close to it at all.
Like ~20% less damage. The weapon speed on horseback doesn't matter.
And the speed bonus makes up for it more than plenty. (lol up to 200% more dmg)
The slow ass speed is a big issue, as well as the damage. We are doing less damage than onehanders, haven't got a shield to protect us from apporaching an archer and our slow weapon speed even makes matters worse: not dealing damage AT all.