Yes,you said it well. I just wanna add that to be useful you have to be more capable, knowledgeable and gain more strength. She only used the relic twice in a day and it caused her a week to sleep,sleep that is comparable to death. I understand the husband's concern because he loves her so much and she did not understand that. What if instead of being useful she will end up as being a burden to him and their people? She have to learn more about her power so that she can prepare the aftermath. If she's able to handle it then she's capable of helping him into the battlefield.
Exactly. She knows nothing about being on the battlefield. Her knowledge of the future can handle so much already. She'll put unnecessary stress on not only everyone around her but mainly herself which is why Kay is afraid of letting her use the relic when she is inexperienced.
You hit it again,agree to what you said
I get her willingness to help and be useful to Kay after discovering she is a relic sorcerer. However, she didn't take into account how he would feel or those who love her feelings if she were to sacrifice so much of her life to build what her husband wants. It's commendable to want to be useful even knowing the risks, but Kay is seeing beyond them and doesn't want to use her like that at all. He cares for her, loves her, she has already been out for a week, so why put her through more than she can handle?