An mid-game weapon that can be found in the 1.0 ice dungeon and can also be equipped in both the mainhand and offhand.
Mega man's buster varient is a semi-auto arm cannon that has a high fire rate, however, it has low damage, and needs to charge for a short period of time after each mag(?).
Zero's buster works a little differently, as with this varient, you can still spam-fire, BUT, you can also hold down the fire button to charge a more powerful shot.