The "B" button is your bullet blade and blocks or erases the orange bullets. It only seems to work once or twice then that is it for a bit. Not sure what builds it back up again. Please contribute if you have info on this. You can boost this, some what, first level when a big creature spits a bunch of orange bullets at you is the best time. Use this weapon as a defense which it was intended and this will unlock eventually as you play. The xbox one game achievement tracker seems to work on this game so you can check your progress.