I've noticed that VERY early on you can get the Unique, two-handed weapon, Wuuthrad I believe it is spelled, but I am over 300 hours in, and aside from Dawnbreaker, I CANNOT find any unique/artifact/one of a kind, one-handed weapons! Are they just not plentiful in Skyrim? By the way, I am not referring to generic, enchanted weapons. What is the deal with this? Where am I not finding them? Spoilers welcome.

Here is the UESP page on unique artifacts. They should all be listed there: http://www.uesp.net/wiki/Skyrim:Artifacts

I always found one-handed uniques were much more common than two-handed.