There are in fact some very, very nice weapons, which have significantly better stats then common equipment. usually those are unique swords and such, they cost a fockin fortune and are even quite expensive to maintain (weapons get damaged, so train your craftsman skills!).
From what I saw during testing, weapons go in some damage range, for example swords had like 3-4 damage (early low quality swords) to 7-9 damage (unique special swords). Please note that these numbers can be completely different after launch.
Also this is not only metric of sword quality:
it also has stat requrement, weigth, defensive stat, length (quite important these ones), charisma modifier (expensive swords gives you better charisma), and especially - DURABILITY.
Low quality swords and weapons have quite a low durability, which often means that you can destroy your weapon during single encounter with armored opponent - simply put, if you repeatedly smash your dull cheap sword against high quality armor plate, it will eventually break down. It was actually very interesting aspect of the game, when you had to really think about what weaopns and armor you carry around, as you are quite limited by weigth.