Ferrus Manus
The Primarch of the Iron Hands Chapter, HE HAS METAL HANDS! He got said hands after wrestling with a silver dragon on the planet he crashed on and dripped the lizard into magma and then the metallic skin of the dragon fused into the skin on his hands. Yeah, GW is skullfuckingly weird like that.
Ferrus, using his shiny metal hands, could make epic weapons that absolutely kick ass but he only used like one or two of them.
Back in the days of the good ol' Horus Heresy Ferrus made a big blingy sword for his good ol' buddy Fulgrim, but Fulgrim found a new boyfriend/girlfriend/hermaphroditic freak. Then decided to screw over Ferrus, Fulgrim totally outmatched Ferrus with his HAWTNEZZ and Ferrus jacked the sword he made for his ex-boyfriend back. Some time later after some epic planning that would EPICALLY FAIL, Ferrus goes with other Primarchs to attempt to kick Fulgrim's and Horus's ass. But then they got totally fucked up by a bunch of reinforcements while Ferrus got assrapes Fulgrim... until he becomes Slaanesh's boyfriend; and proceeds to cut Ferrus Manus's head off. Horus was pretty fucking pissed at this.