@Whatever Well I get your confusion because I too have that thought. In the late part of the story Arena (the saintess)
Spoiler!
leaves for heavenly realm to become a God or something but she promises camilla that she will lend her divine powers to her whenever she needed it. And with this power, camilla cures a sick kid in Korea when she goes back 10 her world one last time. So basically she still has divine powers even If Arena has left and her soul no longer exists on land.
But for Zeno, if he ever vanishes camilla might never use swordsmanship again. I still haven't read a lot of side stories so I don't know the fate of Zeno yet. Well she can always say she isn't interested in swordsmanship so she will never lift a sword or something. I bet everyone will understand because the is very popular after all.
I like to post spoilers for the stories I find interesting because I don't have much time to read novel due to busy schedule you will find me in most romantic historical manhwa comment sections