Quote Originally Posted by fey
Agreed -- which is why Roman-time cavalry was armed with spears and why its charge was so devastating.

However my point was that the lack of stirrups prevented effective sword fighting (or mace/morningstar fighting) on horseback a lot of which youl see in medieval European wars. Without stirrups a rider is not stable enough for this.

Thus, as correctly modeled in RTW, as long as Roman-times cavalry is charging, it's fine. Once it finds itself bogged down in melee combat and not moving much, it's very vulnerable.

Fey
However, swords, etc were effectively used by cavalry, Roman and otherwise, prior to the stirrup; the spatha for example being adopted by the Romans around the 1st century. A rider with stirrups would have some advantage in close quarters over one who didn't, but that wouldn't make the latter ineffective.

The biggest disadvantage for any horseman in melee, with or without stirrups, is that his horse presents a large and generally poorly armoured target, especially the legs, plus the rider suffers deadzones where he can strike and defend because the horse is in the way. To give himself the widest & clearest field of view to attack, the rider has to be side-on, thus exposing the greatest area of his rather vulnerable horse. With attacks to the front, the horse's head obstructs his attacks plus he cannot reach much beyond the horse, again making his mount vulnerable to attack... unless he's using a spear, which does help somewhat but not entirely.