Masteria Expansions, Names and the proof for each

I didn't make mention of it possibly being a bow, I'm just suggesting it would be really cool if they managed to create a way to make a one handed crossbow.
Anyways, its not like it hasn't been done before.

"pistol crossbow"

Kinda supports my "it's a gun that looks like a crossbow" idea.

There are other questions that need to be asked over the possibility of her using a gun.
Isn't the pirate or more specifically the creation of the gun in the maple "universe" something new.
Any information(from other versions quests) over when the pirates were formed as their own class might clarify this a bit, but until then its pure speculation.

We have guns in the data, so the development team definitely has access to them. When using a Mapler as a basis for creating an enemy, I would expect that they wouldn't limit themselves to things which are released, especially when the thing in question is not necessarily even ACTUALLY a gun.

And then again, I might just be overreaching my understanding of the development process. They might have made an empty handed character and pixel-art drew in the weapon, and in not paying attention, gave the monster a one handed cross bow and also happened to make the enemy holding the bow in its offhand.