Stormbringer - it was the first sword I saw as a character in a story, it interacted with the characters, had it's own agenda.
Tron's Data Disk
Tron's Data Disk

I have always had a soft spot for the Glaive from Krull.
Well, to be serious of my favorite fantasy weapon, I like the gun used by Capt. Malcolm Reynolds of Serenity. It seems to be a hand held rail gun of sorts.
have you seen the homemade gauss gun on you tube? https://www.youtube.com/watch?v=TWeJsaCiGQ0
[*]Alien blaster (Fallout)
["The alien blaster is a weapon of extraterrestrial origin found in Fallout and Fallout 2. The alien blaster is particularly devastating as a close range weapon, and along with the turbo plasma rifle is one of the most formidable weapons in the Fallout games to date."]