If you are duel wielding, only that skill is required. I have not played a melee character in DKS, but it is not so much a question of 2 handed swords not being balanced as it is magic damage enchantments being much more effective than in D2:ED.
You really don't have to get the optimal character build in order to successfully finish the game, though. People have played the entire game with an unarmed warrior. Unless you are having persistent trouble with combat, you don't need to worry about the best possible weapon to use (and even then better equipment or an adjustment to stats, skills or strategy may help more than switching weapon types).
