Leia’s modified flashback will allow us to demonstrate this concept quite cleanly, too. Having that much power means you need that much more resolve and strength in your spirit. Which is what sets Rey apart from the likes of the Skywalkers that fell to the dark. “Some things are stronger than blood.”
Now I just need to figure out a way to re-write the flashback voiceover in such a way the conveys my last paragraph.
“She was quick to learn in our training. But Leia knew that a light as strong as her own could cast a terrible shadow within 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.”