It was a light-heavy horse always. I see it is still so. It's still the toughest light horse. It's just that, heavy horses are tougher now; the way it should be in my opinion. I find this change, very good to my liking.
Besides, for those who think charge damage nerfed; yes it is nerfed. But it's not like that you were doing 20 damage with bumps. The main feature of cavalry was bump-slashing, or lance-bumping. The bumps will just do less damage now, but the damage is not that much important as I said. The main benefit of bumping is breaking the guard of the enemy, or possibly knocking him down.
Edit: Umm the eastorn horse looks a bit weird though. 8 difficulty and 6 armor only. Something in the middle between courser and arabian warhorse, manueverable and fast. A good idea maybe, but 6 armor won't save him from much of arrows.