I once made a blade called "Bane of the Falmer." There was an enchanted weapon that came with Legendary Creatures (I think it was dropped by the Boiler, found in Blackreach) that would do extra damage to Falmer. I disenchanted that and made my own sword out of it.
Trying to find a picture of it... I can't remember what its stats were. This is a real trip back in time here...
Still haven't found it yet.
Nope, I found it.
It was a Daedric Sword (this was from long before any of the DLC's were released and before I got my hands on the Creation Kit) that did 84 damage (with smithing improvments; the blade was Legendary). The enchantment itself was 75 additional points of damage against Falmer, and absorb 20 points of health.
That was with either my second or third Skyrim character (either with Lanari the Bosmer, or J'rani the Khajiit Vampire).
A moment of being off topic: I just ran across an
old shot of the original Vulom that scared the crap out of me. It's the eyes. I was not expecting that.
To be honest, I don't really create my own legendary weapons or armor. I might name them to distinguish them from other weapons I have (especially with dual-wielders), but most of the time, they aren't named. I just tend to stick with whatever is in the game.
The items received during Daedric quests could be a little stronger, but other than that, I don't really pay any attention to "legendary" items.