I was wondering if any NPC's dual wield 1h weapons? I was hoping to face some really tough barbarians wielding dual 1h axes or something. Is this a player only feature?

I had a thief come at me twirling dual wielded daggers after my intimidate speech roll didn't work.

They do, it's just not often.

yeah i have seen NPC wield Two one handed weapons several times.

I think thats a leveling thing, I know the "barbarians" near Markath (or how it′s spelled) like to dual wield

Yes,I fought alot of dual-wielding Forsworne.

Once a man dressed in black appeared in the middle of nowhere and chop-chop-chopped by husband down with two blades.

As an aside, apparently marriage turns men into the Skyrim equivalent of couch potatoes because Farkas was absolutely useless in combat after we got hitched.

I have seen a forsworn do that.

Random Dark Brotherhood encounters, they sometimes dual wield.

I've seen that a few times.

I fought a ghostly fella who was waving two one-handed axes. I think it's the only one I've seen, though.