..and a belated Merry Christmas to you too! That's alright, the riddle was great actually, I looked for awhile and just couldn't find it. I enjoyed trying to find the answer though. I can't thank you enough for my Secret Santa present either, it was amazing! Thanks!
Merry Christmas agent Sciencefriction!
Zaknafein Do'Urden's swords are made of... Adamantite.
Sorry about the obscure riddle, but I had to make sure it was something you wouldn't be able to google right away!