Well, technically a speargun. The crossbow in the game uses “rubber hose” to craft when a real crossbow derives it’s power from it’s arms in the same way a bow does. It should basically be the same recipe as the bow with some extra wood for the stock.
Additionally, i’d like to point out that someone messed up arrows and bolts by giving them 0 range in 0.5 and placing their usual range in the weapon’s range modifier. Although i guess whoever did this did so because these ammunitions receive their range from the weapon that fires them, this messes with the way the game usually works by doing things like making it impossible to fire crossbow bolts from rail mounted crossbows on guns.
Although, I’d love to see something like Sam Fisher’s M203 (I’m fairly certain) launcher that you could load with noisemakers, shockers and various other useful items.