So, that was actually pretty good. Until I got to the backstory
Overall you're fine, but giving him a Lost Logia is kind of nope. As far as a I know the only canon character to utilize one directly is Hayate, and I'm sure you know how overpowered she is
There's also no clear explanation of why his device was with him at the Church. You don't need to say how he himself got there, but you should explain why his device was there as well