So far I've been able to Smith + Enchant better weapons than I find, but of the ones I've found/been rewarded with the Ghostblade is pretty cool and the Dawnbreaker is really fine looking.

Agreed - Nothing beats Legendary Daedric Sword with 2 enchantments hehe
But yea, Nightingale blade is cool. Unfortunately, the high level version is bugged and I can't upgrade it at the smith. -.-
Dawnbreaker is cool for lower levels. I love when the undead explode haha
Oh a few other cool weapons are:
Chillrend (Glass sword with frost damage and paralyzing - in a display case, in a later quest in the Thieves Guild chain)
Mehrunes Razor - Daedric quest, starts in Dawnstar with the Museum. There is a chance to insta kill an enemy with that dagger.
Spellbreaker - Cool shield that will create a ward to block magick damage, when you block with the shield (Peryite Deadric Shrine quest)
The rest are useless for me, I don't use hammers or anything 2 handed lol or maces, or staves. Wabbajack psh lol