At long last, I added a few sentences about Kiora. I feel like you were expecting more, but I'm not entirely sure what you want. It's not like we're going to have a long history together, and I would assume figuring out our chemistry would be a large part of the game.
Sorry this took so long to get back to, life's a bitch. Anyway..
You assumed incorrectly.....partially incorrectly...
The very premise of this story is that you are a meister and weapon team who has already proven themselves efficient enough to be specially selected by Lord Death. Yes, you should have a history, OF COURSE you should have a history together!
Please make sure that your CS's history reflects the connection between two people necessary to be a proficient weapon/meister team. You don't need to have a deep understanding of all their hopes and dreams but this whole thing definitely calls for you to know each other fairly well and be able to connect, literally, on a spiritual level.