Since when has sword infantry (apart from legionaries and the like, which are more like big shield infantry than sword infrantry) been able to consistantly beat spear infantry? The spear is the superior weapon, and the sword is supposed to be for backup.

Indeed, in a duel with equally skilled fighters, one with sword and the other with spear, the spearman will win more often.

It seems to me that there should be no "sword infantry;" I can't think of many times when soldiers were equipped with swords as their primary weapon. Again, I make an exception for legionaries, because while their swords are arguably their primary weapons, it is their shields that makes the soldiers so effective and are almost really their primary weapons, if not offensive ones. In fact, if I were to be placed into a battle and was given the choice of either a scutum or a gladius, I'd take the shield!