Because not everyone can afford a firearm, most of the pirates or crew members you will face carry a cutlass. Simple and efficient.
Those professional warriors carry a good musket and are well enough organized to never run out of ammo.
Not much is known about ghosts, except they used to be dead. Killing them again with traditional weapons won't work.
Edward Teach aka Blackbeard fights with 2 pistols and a belt full of ammunition!
I have 2 variants of him (different belt) - which one do you prefer?