Ok, now most of you know of the Transmogrification Process that was released during Cataclysm. Well there were many people that started making comments about their "favorite" weapons and armor and how they can't get them anymore because they are no longer obtainable in-game, for example, the dungeon set 1-(I believe)3; CORRUPTED ASHBRINGER; Atiesh, Greatstaff of the Guardian; Andonisus, reaper of souls; Etc., even items that never made it as in-game content or never released to public, like Purified ashbringer, frostmourne, alternative-model warglaives, etc.
Well my idea was to create a new vendor that sells these items without any stats but are meant for transmogs, like the challenge gear of MoP. Now here is how I think they can do it too, now we all know that with every expansion so far, an addition was made to the Caverns of Time in Tanaris, now I figured that when Blizzard goes and makes their next set of content for CoT, they can also implement a new vendor beside the quartermaster, calling him/her a "weapons of legend vendor" or somethin of the sort, but in order to purchase the certain piece you want, you have to meet certain criteria, now each item will have different requirements, like for example, [Frostmourne] - requires the ICC 10-man or greater achievement,
*edit* like I said in the comments below, they won't look exactly the same, there will be a very visible difference in the model, I can try and post an example of one when I get done with it.
Corrupted ashbringer - Complete all wings of naxxyramas 25-man heroic in one session,
pure ashbringer - complete ICC 10 or 25 man heroic with the Corrupted ashbringer item in your bag for the entire raid,
I also wanna hear your guys feedback on this, and hopefully, someone from blizzard can see this and at least suggest this idea to the production teams, but maybe I hope for too much.