I agree with OP, however also:
- make horse corpses (potentially) lethal
- make trample damage more random (chance of kill / incapacitation), with a longer stun when trampled
- lower horse HP by 30-40%, no armour for unarmoured horses
- running into chambered weapon, esp. spear inflicts damage
- subject infantry to some effects of inertia (much slower spastic dodging, etc, changing direction while running harder)
- jumping and attacking for infantry lowers damage to 1/3rd except maybe for jumping frontally with a spear, chance of injuring yourself
- jumping and being trampled increases trample damage 4x
- archers need to stop for a few seconds and catch their breath to shoot accurately
- archery damage increased significantly vs low-armour targets, same vs armoured except helms protect vs headshot / slash / whatever
- gravity increased (affects all ranged)
You know. Something for everyone