I'm not sure I like the idea of named "unique guns", I see why they exist in game terms, they're a reward for exploration or killing "bosses". But on the other hand in real life, it just doesn't work that way.
Yes there are things that can be done to make a gun better than a 'stock' gun: a match-grade barrel, hair trigger. But those things are what gun mods represent in FO:NV.
It just seems like too much of a fantasy game thing to me. It's essentially "enchanted weapons" following the old fantasy trope.
Now I'm not against unique guns, but I think they could be done better in-universe. FO1 did it great. They had a unique gun, the .223 pistol, but it wasn't named like a fantasy weapon, it was named like a real gun.
So sure, have one, call it a prototype laser weapon or call it a longbarrel revolver but don't give it a cutsie "enchanted weapon" name.