The Blunderbuss needs to be loaded with Gunpowder to be able to fire. However, it can be used as a very weak melee weapon while unloaded. When loaded, a small red light can be seen on it, suggesting it is a matchlock gun.
Because the Blunderbuss deals the exact same damage as the Gunpowder used to load it does, this makes it much easier, predictable and practical to use from range when compared to having to light Gunpowder on its own on the ground.
Unlike the explosion of the Gunpowder on the ground, the Blunderbuss will not cook meat or set any flammable items on fire, this can make the Blunderbuss all the more useful for boss mobs.
The Blunderbuss can also be crafted using 10 Oincs or 1 Centapiece Oinc. If using Centapiece Oinc, 1 Tenpiece Oinc will be used and 9 Tenpiece Oincs will be returned.