The Crossbow is a ranged Weapon in Spelunky 2. It can be bought from shops, or stolen from certain NPCs.
The Crossbow is a ranged weapon that shoots a single preloaded bolt away from the player. If a bolt comes into contact with a wall it will remain lodged for several seconds before falling down. Bolts must be retrieved by the player to reload the weapon, which then happens automatically. It is also possible to load a regular arrow into crossbow, which do not stick into walls, instead bouncing away. The crossbow does 2 damage by default, but the blue crossbow bolt is capable of killing Vampires (and Vlad) in a single shot. The bolt does not need to be fired to do this.
The bolt's ability to annihilate Vampires likely comes from the belief that a stake through the heart of Vampire is the only way to kill them for good.