Is it possible that the Final Shape is the Witness' end? I think it would make sense when it comes to the Sword Logic. Is it possible that the conquest of the Witness is just a search for someone strong enough and brave enough to challenge him and kill him? Kind of like the Ebony Warrior from Skyrim.
Maybe spending eons as a immortal in a mortal realm has made the Witness suicidal and he just wants it to end.
Edit: Maybe that's why the Witness holds such a grudge against the Traveler. The Witness knows that the Traveler can defeat him but just refuses to land the killing blow.
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In a way this actually kind of works with the way oryx interpreted the sword logic. It may not be the end the witness is going for, but could be an acceptable plan B like oryx and his touch of malice failsafe plan