I think these are really good points and ideas. RotJ really works at the end because Luke faces so much temptation. Rey has a tending towards the dark but that temptation could really be emphasised.

Speaking of the dagger, now that it operates by whisper rather than the absolutely contrived pointing, it’s remaining flaw as a plot device is that the good guys stumble upon it in an absolute quirk of chance. Perhaps it could be implied that it’s somehow drawn Rey to it- either through Palpatine’s machinations or its own.