It makes plenty of sense for Ashbringer and Doomhammer to be in player hands. Doomhammer rejected thrall and chose the PC shaman. Tirion Fordring died and the PC paladin took Ashbringer from the dreadlord who was trying to darken it again. Frostmourne was shattered into at least three or four pieces. The PC DK worked with Bolvar LK during Legion to make a new weapon from those shards. And succeeded. That’s what frostmourne is now, two toothpicks. How can someone mog OG frostmourne when it doesn’t exist in that form anymore and the only wielder of it in its mourneblade status was arthas?
I guess you could go to maldraxxus and beg the Primus to make you a fake for your shiny collection. Maybe he wil!