“She was quick to learn in our training. But Leia felt that her passionate nature would make the easy path to power too tempting for her. She surrendered her saber to me and said that one day it would be picked up again by someone with the spirit to face that darkness.”
Maybe this aligns best with her characterisation as a little brash, sharp, quick to act on her passions? This way, she knows herself well enough to be wise about temptation, and preserves the idea that Jedi fight or seek power as a last resort (and normally train from a much younger age than this specifically to learn to manage that fear/anger/hate/suffering path), whilst keeping it as a smart decision she’s chosen to make. But here, ‘the easy path to power’ is a direct allusion to the dark side, as seen onscreen elsewhere, and implied in this dialogue as a part of the Vader bloodline.
The only other thing I still question is the reason for Kylo and Rey needing to fight. I agree that they need to, to solve some inconsistencies and to keep TFA/TLJ as part of Palpatine’s plans, but I think there’s an angle where we keep Rey as the intended heir and Kylo as the tool, but we can tie it into Kylo’s ‘other plans’ for his relationship with Palpatine and Rey too:
“Palpatine wants me to fight you.”
“Serving another master?”
“No. I have other plans…”
…
"Palpatine influenced the Force itself into creating life. First my grandfather, and then you. Both created to be his chosen heir. You… are a rightful Palpatine.”
"Now, the Emperor wants us to fight each other, so you can reach your full potential and can claim the throne. But he doesn’t know how much our conflicts strengthen our connection, Rey… a bond, not of blood, but of raw power in the Force. We can end him and the Sith, and create a new order, together…”
This way it’s all aligned with what we’ve seen onscreen, and with the idea that Palpatine’s behind Rey’s origins and also using Kylo to push her deeper into the dark, but he’s also inadvertently created and reinforced the Dyad bond, which Kylo believes makes them strong enough to challenge him. It also adds a little extra ‘meat’ to what Palpatine consumes from them when he’s suprised to see the bond - it’s a power that we can interpret as some mix of Palpatine’s ‘force influence’ and them amping each other up through their clashes. (We don’t need to get explicit about that, but it’s there as a possible read that works with what’s onscreen.) (And, very minor note, but it also adds a little further irony if we read that Snoke ‘bridging their minds’ helped forge the bond, since he was Palps’ puppet.)