@Noll:
Mongolian Horse-Archers
They were trained to shoot while raiding a horse, they were very precise (They were shooting only in that half a second when the horse’s legs are not touching the ground), and they had a very hard and strong bow that pierced through heavy plates like a gun through butter.
In Richard Armour’s satirical history of warfare, he states (as I recall) that Atilla the Hun’s cavalrymen used formidable double-handed battle axes which could split in two an enemy rider and his horse, but that sometimes the Huns would get lazy and use their axes one-handed, with the result that the enemy rider would be split in two while his horse would escape with only a slight nick on its back.