Instructions
Travel to any blacksmith shop in any city in the game. The blacksmith shops allow you to purchase upgraded weapons.
Talk to the blacksmith in the shop and select the crossbow for purchase. 12,800 Florins will be deducted from your money bag.
Walk outside the blacksmith shop and open your item menu. The crossbow will appear in the upper right-hand portion of the menu. You will see a number next to the crossbow denoting how many bolts you have available for use.