antiquegeek

Exactly, I see Nightblood as one of the only ways to truly get rid of the souls of these Ancient Singers who are inhabiting the main power in Odium's forces. Obviously, Szeth and Nightblood can't kill all of them (Right?...) so that's not the whole story here. Remember that the honorspren in Shadesmar mentioned having Nightblood pass through their fortress a while back, as well as the Nightwatcher having told Dalinar that she could give him a sword that bleeds darkness for his boon. I believe that this has been known as one of the strongest weapon against Odium for quite some time, and Vasher probably specifically was contacted to bring it in a desperate time of need.

I think it's about humans settling in Shinovar when they first came to Roshar, which we know is protected from the storms by a mountain range that probably is signified by the wall in this story. Us finding out we are monsters would be the secret that broke the Knights Radiant.

Unity also, you should use [OB] in your titles for spoilers

I had this exact same thought while reading! I wonder how many Unmade were imprisoned (possibly all of them?) and if them being released would portent the coming of a Desolation.

So the flashback where Dalinar was fighting the Midnight Essence, the Radiant says he is not sure who released it. This almost seems to imply that Re-Shephir was already imprisoned.