Hello, first time poster, I should reread the latest book. My main thought from the thread was an observation about the comparison with the duel Sadeas agreed to. I think it is possible that Adolin ends up being the champion of the shard previously existing as honor because of his association with duels. Which suddenly gives me the image of him running into OD in a back room and killing him.
As for Odium's choice, Adolin, Moash, Taravangian seem reasonable characters but none of them seem just right. Maybe the knight radiant working for Taravangian or one of his other subordinates. A Vorin priest or one of Shallan's family could be interesting but would need development.