Which Assassin's Creed game introduced the hidden blade's iconic wrist-mounted design?

The original Assassin's Creed introduced the series' iconic wrist-mounted hidden blade design.

The 2007 game presents the hidden blade as a concealed weapon used by Altaïr Ibn-La'Ahad. It folds beneath the forearm and can be extended when the Assassin is close to a target, making it suited to stealth and surprise rather than open combat.

The weapon became one of the franchise's defining visual symbols. Later games expanded its functions, adding variations such as poison blades, double hidden blades, rope darts, and mechanisms that did not require the traditional finger sacrifice shown in earlier lore.

The hidden blade itself was not invented by the second game, although Assassin's Creed II popularized additional equipment and gave the weapon more upgrade options. The first game established its basic design, its relationship to the Assassin code, and its role in the series' assassination missions. Its exact operation and historical plausibility are fictional elements of the franchise.