In initial charge certainly. But when both units are in melee shorter weapon is much more effficient since it is less clumsy and it is quicker.. Cataphracts are for inst. using maces in close combat (alt+click) and that's much efficient too...
Cataphracts Cataphracts are extremely heavily-armoured cavalry who can turn a battle with one thunderous charge. They are the ultimate in shock cavalry, an armoured battering ram to crash into an enemy position and sweep aside all who stand against them. They are armed with heavy lances for the initial charge and maces for use in close combat. They wear armour that is almost unmatched for weight and protection, and their horses are similarly armoured. On the move they are a wall of metal bearing down on enemies, tipped with razor-sharp spear points. Their armour is their main strength, but it also means that these troops can be quite ponderous and slow moving. That said, sheer weight means that they can often break through (or ride over) an enemy line without too much trouble.