I believe the part at the end has to do with the mission to get more honorspren that Kaladin and co. are about to go on. Possibly Odium knows of Syl's status as the ancient daughter which could possibly make her some sort of queen of the honorspren that are left. The honorspren could help clear shadesmar of the voidspren if recruited fully to the side of the knights radiant and supply team honor with more windrunners as well as some valuable information.