Yeah i saw this post from EffeminaT on that thread:
''I believe I've discovered the beginning stage of this quest
(spoiler)
After completing Arniel Gane's quest, you have to take Keening, and travel to Blackreach. In the main area of Blackreach, somewhat near to the Silent City, there is a small path that leads under a natural stone bridge. There is a small opening under the bridge, and in the opening there are two pedestals. If you activate the pedestal on the left, Keening will be removed from your inventory and placed on the pedestal (note: if you want to try this out, save before doing it, because you can't get the dagger back after you do it). I've yet to find any item that can be placed on the right pedestal, but it definitely seems like there must be some cool secret that is revealed after finding the item.''
That's what he said, and i don't think he is lying, but i can't confirm because i don't have the game near me right now

Can someone confirm? And maybe take some pictures and/or film it so we can see?
Because i was thinking... If you can place Keening there, you should be able to place Sunder in the other pedestal(even though Sunder isn't in the game.. i think) and that will obviously activate something. I was thinking, maybe when you activate it you'll get the Wraithguard that will make you be able to use the otherwise unusable enchants on Keening!
It all does make sense... Unfortunately, all the ID's and stuff have already been found and thanks to noclipping, there are no unexplored areas on the map left... So this just HAVE to be a DLC, right? It all makes sense!
Please tell me if you think i'm correct..


Thanks for dedicating your time to look for.. stuff