Crossbow

The Crossbow is a weapon in Assassin's Creed: Altaïr's Chronicles and Assassin's Creed: Brotherhood. However, this weapon was originally seen in the introduction for the first Assassin's Creed, but was not included due to historical inaccuracies.

After being spotted in concept art and being mentioned in the E3 2010 Single-Player walkthrough, Jean Francois Boivin confirmed that long-ranged weapons, such as the crossbow, will be available for use in the game, especially in advanced horse combat. Some guard archetypes (such as the Crossbowman) will also have the crossbow as a weapon. Ezio is able to use the crossbow in melee combat, attacking guards with the metal lathe, then shooting them once they're on the ground. In the third developer diary, it was stated that the crossbow will be upgradeable, however, how you do this and what you upgrade is unknown.

The max amount of ammo is suspected to be 25 bolts. Ammo is supposedly purchasable from blacksmiths. The way the crossbow is fired seems to be similar to the pistol (lock onto an enemy and presst the "shoot" button then diamonds close in to form a white line), but faster.