In native the Two Handed Sword is usable on horseback, but who cares about that... A better argument is to examine the stats and try to figure out why this sword can't be used on horseback. At 110 length this is still two less length the shortened military scythe. The weight is 2.2, however the Persian battle axe is 4.7. The difficulty of the Two Handed Sword is 12 right in the middle relative to most weapons that can be used on horseback. The thrust damage is less then both the Heavy Bastard Sword and the Longsword, and while the swing damage is greater by 1 for the Longsword and 2 For the Heavy Bastard Sword, the speed of 96 for the Two Handed relative to the 99 speed for the Long Sword and 100 Speed for the Heavy Bastard Sword. I addition to all that, the increased upkeep relative to all the above mentioned weapon, I see no justification for disallowing the Two Handed sword from being used on horseback.