So Kartein knows about Kayden's health state?
They already explained that Kartein is very vulnerable when he's healing someone. That's why Kayden would keep watch when Kartein healed Jiwoo and the old grandpa union man. If Kartein were to heal Kayden, he would be left unprotected and vulnerable while healing Kayden. Kartein puts himself at risk when he heals.
Tbh its not that .cuz no one knows their location and they can literally do healing without a danger its just if he did heal him it will make story less mysterious cuz currently we all are unaware of how strong kyden is if we knew its his full power than we have already estimated his and jiwo's position we still don't know how strong kyden is or can jiwo actually gonna surpass him
Woman, THATS YOUR DAUGHTER IN LAW! Take your man AWAY like a GROWN UPPP