Way back when I started my current fortress, I got this as my first artifact:
And it was literally my first artifact, since this is my first fortress! It's worth an entire 2400 dorfbucks, so it really boosted my fortress' wealth when some dwarf hammered it out. Oh, and I'm pretty sure it was the result of a possession, so I didn't even get a legendary mason out of it. That's the exact instant I knew that DF and I were going to be best friends.
As for my best at not being underwhelming artifact?
Value-wise:
Worth 177600 dorfbucks. Although the instant legendary armorsmith was valuable enough.
Most...interesting...:
The game says the dwarf who made it doesn't have a great aesthetic sensitivity, but it was clearly very wrong about that.
Oh, and the war hammer depicted on said loincloth is
this. My personal favorite in this fortress. Decorated with turtle bone/turtle shell, encircled with iron/pig iron, and has an image of itself on it? It's almost poetic.
EDIT:I forgot the absolute best thing about that war hammer. My first hammer was pretty awesome(although making sure that she never had the ability to pulverize criminals probably helped - no sheriff or fortress guard means no hammerjustice either) - a season or so after she came to my fortress, there were several goblin ambush parties that attacked at once. She took it upon herself to singlehandedly kill eight goblins, earning himself a title. My hammerer's full name now?
Erush Atticsprays the Image of Evaporation. I gave her a nice big sand tomb with lots of green glass furniture(hey, she liked sand and the color dark green) for that. Atticsprays spent some free time evaporating a groundhog and two wolves when it was peaceful, but come the next goblin ambush she charged right back out to kill some more...except for the part where she was killed before she got to smash anything. A season or two after this? One of my smiths gets possessed, and the result is that iron war hammer. Clearly Ms. Atticsprays the Image of Evaporation wasn't quite done pounding gobbos with a hammer yet, so she made sure that a future hammerdwarf could keep on evaporating goblins in her place.