Hidden Gun

"It seems to be a kind of arma da fuoco - but as small as a hummingbird!"

- Leonardo da Vinci, regarding the pistol's design.

The Pistol, which is also referred to as the Hidden Gun, is one of the expansions of the hidden blade invented by Altaïr Ibn-La'Ahad using the Apple of Eden. After discovering the design for it on one of the Codex pages, Leonardo da Vinci managed to craft one for the use of Ezio Auditore.

Description
The pistol consists of a small firearm with a very short barrel that, if aimed properly, can kill a target from a distance. Though an excellent weapon for assassination from afar, it will give away its user's position immediately after firing, due to its loud discharge.

Up to 6 bullets may be held at a time, and can be purchased from any blacksmith. However, they are quite expensive, as one bullet costs 175 florins (149 florins with full discount in Monteriggioni), which is three and a half times the cost of a throwing knife. Alternatively, bullets may also be obtained by looting dead guards.

Combat
The pistol takes about a second and a half to completely aim, though it can be fired before it is fully aimed. Firing immediately without aiming is not advised, as even at close range, it is highly unlikely to result in a hit.

Aiming the pistol within guards' lines of sight will automatically make them suspicious. When in combat against a small number of guards, aiming it for several seconds will also cause the group to lose morale and eventually flee, though this tactic cannot be used for Brutes.

Though not recommended, it is also possible to quickly switch to the pistol during a battle, and take a random shot from as close as possible to an enemy, before resuming the fight. Despite its low success rate, this method can potentially pick off immobile opponents, or quickly eliminate enemies without the need for counter-kills.

Advancements
In Assassin's Creed: Brotherhood, the aiming method of the pistol has been modified, and no longer seems to require a trigger pull to be fired (an invisible mechanism similar to the hidden blade's). Though perfect aim is achieved much more quickly, the bullet can only be fired after the shot is fully charged.

Ezio also gains the ability to dual-wield the pistol alongside a medium, primary weapon. This allows him to easily switch between short and long ranged combat, using the pistol with his left and a sword with his right. He may also use the pistol for counter-attacks and point-blank kills.

After reuniting with Leonardo da Vinci, Ezio is able to purchase an upgrade to his pistol that allows him to fire small Poison Darts from it, in addition to bullets. These darts are usable when the poison blade is equipped, and share its effects.

Codex Description
"Success! We have found a way to alter the structure of the hidden blade so that it can be used to launch small projectiles. It is capable of grievous damage – even from great distance. I confess, the means by which I came about the discovery was... risky to say the least. But I have found that in small doses, and with a focused mind, the Apple can be used without ill effect. Or so I hope.

"The knowledge of projectile combat is not new to us, having been observed amongst our Eastern neighbors. But their weapons were much larger – and insufficient for our needs. I have now found a way to miniaturize their designs, embedding their fiery weapon into a form that can be worn on the wrist.

"We have also refined the formula for combustible powder, such that common ingredients might be used. This is a dangerous bit of knowledge and it is best shared with only our closest allies..." -Altaïr in Codex Page 28.

Assassin's Creed II

 * Often when the pistol is fired, a dog can be heard barking. Though not a surprise as dogs tend to bark at loud noises, no dogs are seen or mentioned in the game.
 * Both the pistol and throwing knives are disabled in the Secret Locations that require the player to chase an Agile.
 * Ammunition can be found as an item when looting the bodies of any deceased guards, whether or not they are arquebusiers.
 * The pistol does not kill in a single shot during the battles with either Dante Moro and or Rodrigo Borgia, though it is just as effective as usual when the player is required to assassinate them.
 * Due to its interconnectivity with Assassin's Creed II, it is possible to obtain a variant of the pistol that fires throwing knives instead of bullets in Assassin's Creed: Bloodlines.

Assassin's Creed: Brotherhood

 * The pistol is also a multiplayer ability for multiplayer characters; though it is unknown if they actually possessed the weapon, or if Abstergo simply added the ability in the Animus.
 * Four additional bullet slots for a total of ten slots can be purchased for 30 Units on Uplay.
 * For reasons unknown, counter-attacks and executions do not use up bullet ammunition.
 * During a kill-streak, the player can hold down the attack button while targeting an opponent, causing Ezio to perform an automatic double kill with his sword and pistol, using up ammunition in the process.
 * The sound of the pistol more closely resembles that of a musket, rather than the cannon-like sound in Assassin's Creed II.
 * The Assassin Apprentices' pistols (obtained by rank 5) use the same firing sound as heard in Assassin's Creed II.
 * Strangely, the apprentices' pistols are much weaker than Ezio's, taking up to three shots to kill a guard; though this may be attributed to Ezio being more skilled in wielding the pistol.