Artifact Weapons, Faction change and Mage Tower

I recently wanted to go back and collect some missing artifact appearances. When i went to do so on my Paladin, I found that I cannot find my artifact weapon (Ashbringer) at all in my bags or bank bags.

I opened a ticket and a GM got back to me and said that the Paladin in question did in fact have the Ashbringer artifact weapon in his inventory. He then said some stuff about account transfers and that I had a faction change a few years ago.

This information leads me to believe that when I changed factions, I lost my artifact weapon for all specs (even though i only care about Ret/Ashbringer).

So i have asked the GM if i return my Paladin to Horde, the faction I was on when i completed the artifacts/class hall, would i then have it back in my possession? but have not gotten a response just yet,

My ultimate goal would be to go back and get the additional mage tower skins as I have the base Mage Tower skin (Shattered Reckoning) and the “A Challenging Look” achievement on said Paladin.

So my question is this, since I do not have the artifact weapon on the Paladin that did the Mage Tower after the faction change, if I go back and do the questline to get a new artifact weapon, would i then be able to get the additional appearances for the Hidden mage tower appearances? For example, if i go back and get a new artifact weapon on the Paladin that has done the mage tower achieve/base from back when I was on Horde faction, can i get the fourth appearance by getting a new artifact and equipping it and defeating all legion dungeon bosses with it?

I know this is a pretty complicated situation, but would really appreciate if anyone has any thoughts, answers or solutions. It is driving me nuts and frustrated because i did the content and beat the challenge for the Mage tower appearance, but if I am not able to get the additional ones just because i faction changed and lost my artifact weapon, it seems that would a massive oversight on Blizzards part and very unfortunate for me.

Thanks