I've been perusing threads about Taln (who he is, where his Honorblade is, etc.) and after reading about the quote mentioned on previous pages concerning "The Gift and Words... Now his." I was curious what "The Gift" may be. Another theory floating around suggests Taln may have actually been on Roshar for 6-7 years and had contacted Shin folk, namely Szeth thus starting his belief in what caused his punishment. If the timing theory is true, and Taln has been around for awhile, what if he encountered Gavilar, and the black sphere he found is The Gift?
I'm aware of the WoB that states the light in the sphere is a "different" light, likely some sort of void-light, but perhaps it is some bit of Odium's investiture stolen by Taln as he was returned to Roshar for this Desolation? Maybe every Desolation the Heralds returned with something similar? I couldn't begin to imagine what the use of it could be for if this is the case, I just thought it may be interesting.
This is all wildly speculative, but it intrigued me when I thought about it and I figured it may provoke some interesting conversation.