In the pre-chapter text (can't remember what it's called) of the Rhythm of War chapter 'A Cage Without Bars,' Harmony says that he is looking for a sword that embodied the two aspects of the power he holds, Ruin and Preservation. In the previous pre-chapter text he mentions being hampered in his ability to act due to his two held Shards being opposites, so is it logical to think of this as Harmony seeking a champion to act on his behalf against/with other Shards? If so, I have a theory.
I'm not sure if there's a running theory on this, but the main Cosmere character that comes to mind for that is Kaladin. He's trained/training as a surgeon and is a skilled fighter. Particularly in The Way of Kings, there was a constant internal dialogue about whether Kaladin or his father were correct in how they could protect: Kaladin choosing to protect using force while his father protects through medical care. Kaladin is currently in a spot where he can protect using both methods, acknowledging that he needs time to deal with his PTSD and depression but is enhancing his abilities in the medical area.
The main barrier I see to this potentially occuring is that due to Kaladin's nahel bond with Syl he is anchored to the Rosharan system, as per Mraize's conversation with Shallan/Veil/Radiant in part 1 of Rhythm of War. Now this is entirely conjecture, but I am assuming that by the end of Book 5 several key things relevant to this will occur: a way of transporting Rosharan Lights to other systems will be discovered, which will be linked to finding a way for Connected individuals to move outside of their systems as well. While I don't believe Kaladin is intended on being a main character for the back 5 (correct me if I'm wrong), that doesn't necessarily mean that he won't still be a major player in another form like being a champion of a Shard that isn't "native" to the Rosharan system and is thus not present for Rosharan events all the time.
If there is an existing theory thread regarding this, could someone please point me in its direction?
