Not enough Divine Edge...
Literally, Divine Edge is the only way to get past dragons. (Except the rare cases where the dragon isn't beefed up in damage and the "Trigger Knight" actually can tank, but that's only happened once in twenty runs for me)
Out of all the runs I've had, I've only seen Divine Edge shop (Grim Shop) pop up once or twice every 5 runs. Therefore, the Trigger Knight always faced a demise when a dragon decides to spawn on me.
Overall, it's a good and original game, definitely needs to be put on as an App as others have suggested, and glad to see another game from AtelierLucid! ^_^
Only suggestion I can make is to make Divine Edge shops appear more often. But then again, I probably have bad-luck :D