Cool submission. It's pretty funny to become hilariously overpowered. It would be really neat if there was some trade off for getting a larger slash attack, more wind up or cool down perhaps. It would be neat if there were more upgrades, even something like scaling up the size of the enemies so they move slower, have more health, and give more exp, for example. I think you could really take this idea up to 11 and it could be really fun.