Debaster, Ebony Blade, Voldrunge, Umbra, Mace of Morgan Bal, Nerveshatter...
Just the top of my head for oblivion...
Molag Bal mind you. As for actually unique as far as looks go there aren't too many more. But as for ones with a unique name and enchantment you only see once there are a ton. If I had to choose between a unique weapon and a regular one with the same model I'm taking the unique one, even if it doesn't have an enchantment on it either. And if you go into other things that are unique you have the Scales of Pitiless Justice, The Grey Fox's Cowl, DB armor (not exactly unique but it looks cool), etc.