The protagonist's concealed wrist weapon in Assassin's Creed Origins is called the Hidden Blade.
The Hidden Blade is a signature Assassin weapon worn on the forearm and designed for close-range, stealthy strikes. In Origins, Bayek of Siwa uses one after receiving it from Aya. The weapon is central to the series' visual identity and connects the game's ancient setting to later Assassin traditions.
Assassin's Creed Origins was released in 2017 and is set in Ptolemaic Egypt during the first century BCE. Its story follows Bayek, a Medjay, and Aya as they become involved in the early formation of the organization that later develops into the Hidden Ones. The game presents the weapon within this origin story rather than as a fully established medieval Assassin tool.
The Phantom Blade is associated with Assassin's Creed Unity, where it combines a hidden blade with a ranged mechanism. Leonidas's Spear is an artifact used in Assassin's Creed Odyssey, and the Wrist Bow is associated with other series equipment. These are distinct from the classic Hidden Blade.