Hi there, thanks for the feedback!
1. When I tried to use the Items option in battle the game crashed.
I can't replicate this bug somehow, are you able to get screenshot of the error? Thanks!
2. The battles appear to be way to difficult. I keep getting curb-stomped by your garden variety blue slimes!
I've reduced initial battle difficulty a bit in the updated 0.1.2 version. However, if you want to make Ban become stronger, please make sure to finish Haves's quest because after that you can buy enhancing potion from him :D