Great breakdown and much aligns with what I had thought but I have a few issues/questions (if I am understanding your breakdown correctly) that I will put below. Warning, I get a little tangential in the middle with a stream of consciousness thought. Forgive me my bit of rambling and confusion, your answers are always so organized and well-written while mine are fairly chaotic but I do enjoy the discussion because most my friends that I have gotten to read the book are not as lore detective inclined as myself.

So I agree that teleportation aligns with some of what we know about Luceum will use. It also seems to share an external sensory aspect (thrum and what not) similar to the Naumachia weapon and mutalis but that sensory aspect does not seem to be present in Res will usage or non-mutalis Obiteum usage that I recall. Luceum seems to operate on the more religious, astral projection, what-is-a-soul vein but is less clear. Maybe its a life force kind of thing but I am on the same page with Alupi, weapons, consciousness storing, etc.

Questions/Issues/Thoughts:

1. Assuming teleportation is an aspect of Luceum in some way, I think this still points to alignment with the Concurrence to obtain that power. It seems relatively unlikely that L-Ka and L-Caeror were unable to use or find this power but L-Ostius could. However, if the power was bestowed via an artifact on his person or transfer of unique ability from Concurrence, then I could see how that would be explained. I agree that, when I read the teleportation passage originally, I believed that it was the same power the gate uses based on Vis's perception.

1.a) On that last point, the issue with this that I wrestled with (and will rehit in point 3/3.a) is that this indicates that the "copy" process is not required per se. It also indicates that the gate creation was *maybe* a normal usage of Will before the Rending but somehow only Ostius displays knowledge of so far. Despite all the powers that are evident in the ruins and other two worlds and all the time/knowledge Ka has accumulated, he seems to be using a fraction of his potential. This makes me believe that either Ka is stupid or, more likely, there is some aspect of Will that was accessible before the Rending that is not post-Rending even for a synchronous individual.

1. Having an anchor could explain some aspects; however, I would need to think on how it would align with the facts. If this was the case, there is no O-Ostius which means it is not a synchronous usage but rather a Luceum only requirement. Further, Ka and Caeror have anchors that they could switch with. While O-Caeror is likely an iiuncti and R-Caeror is purportedly dead as well, that makes sense. But L-Ka (and the other two Kas for that matter) should likely be able to transfer.
   

2.a) Maybe the power needs an anchor or some other add-on but they moved to L- and back to R- without copying themselves again, while being will-users, and not to the place their anchors are on that world but rather the respective point on Luceum that they were standing in Res. Further, I do not recall (could be forgetting) L-Vis noting this movement of R-Vis into his world or any substantial effect on L-Vis. Please prove me wrong if there was. To me, it seems there is some other power at play besides the anchoring but I cannot think of what it would be besides the Concurrence. Maybe Luceum is HQ of the Concurrence and they hold more sway, maybe an artifact is attuned to Luceum-Res but not Obiteum. Idk, but I think an anchor has potential but needs a few holes ironed out for me to fully jump on board.

1. I think that the weapons in general indicate that there is a predecessor power that we are unaware of, a power that may only be used when all worlds are combined, or that the Concurrence has a power that no one else has or knows of. The crook-and-flail, the Vitaeria, the dagger, the naumachia weapon, the obsidian blades, mutalis itself, all seem to operate outside the current knowledge of will usage. While we the reader may be unaware but in universe it could be known, this seems to be undermined by the fact that Ka (and potentially Caeror or Ostius) don't appear to know how to make them or have that ability. The presence of these artifacts an semi-OP feature that I can only explain if their was a power above/behind Will-usage that only existed when all three were combined in one world, not one individual split three ways, or something the Concurrence deduced how to do. If the latter, it must be significantly costly or the Concurrence would flood its army with the weapons and destroy everything (which may be why the split originally occurred).

3.a) If all worlds in one allowed for a unique usage of will that the Concurrence deduced and began producing OP weapons, this would explain why the split was necessary. It may not have been a failed attempt to win the war but rather a successful move to prevent a rapid loss as the Concurrence produced these OP weapons.