This is a really nice system from what I've read. I'm still looking to get into an actual game (no dedicated Discord Servers or subreddits yet, which makes it harder), but I'm really looking forward to trying it out when I do.
Quick question regarding upgrades. In the theme of granting further player agency to character customization, and to incentivize the recovery of Angel Scraps (as opposed to just using them for battlefield repairs), would it be 'kosher' if a GM were to make it so that players had to spend Angel Scraps to apply certain upgrades to their Hymnals? Not all upgrades would cost Angel Scrap, just certain ones.