Fist

In Assassin's Creed the fists are the weakest form of fighting available to the player. Guards will not intervene with a fistfight, unless the player is attacking a guard. However, if the player draws a weapon they will attack.

Assassin's Creed
Altaïr's fists are also the only weapon he can use to interrogate a target without killing or causing them to run, even though the target is always assassinated once Altaïr has his information. When attempting to pickpocket a thug for throwing knives, if he notices Altaïr stealing from him, he may start a fist fight. You can choose to punch back, or you can draw one of your swords and he will immediately flee. The latter will attract the attention of nearby guards if you don't put it away immediately. As weak as fists are they are your only weapon as a novice but don't get used to them because you are only a novice for one mission.

Assassin's Creed II
In Assassin's Creed II, the main character Ezio is more skilled in a fistfight. Instead of the wayward haymaker of his ancestor, he can preform combos, as well as being able to counter other fistfighters. He may also Disarm those with weapons and use them against opponents. The special attack while unarmed is to lean down and sweep some sand into the opponent's eyes, opening the weaker enemies to an instant kill.

Fists also becomes a more viable weapon when the Metal Cestus, a hard steel handguard that strengthens the attack of the fists, becomes avaliable for purchase.

You can earn yourself the achivement/trophy, Messer Sandman, which is worth 10g or a Bronze trophy, by using the sand throwing move on 4 guards at once.