The Secret Saturdays Wiki
"What's a Claw?"
―Zak Monday

The Claw, also known as the Hand of Tsul 'Kalu, is a multi-functioning device which serves as Zak Saturday's primary weapon. It was created by Doc as a means of helping Zak learn to control and focuse his ability to influence and control cryptids. It glows when Zak is using his power.

It contains a spring loaded cable and telescoping shaft. Zak has used it as a grappling hook, to snare objects from a distance and to swing from, and as a vaulting pole. On the end of the Claw the head is similiar to the cryptid's head on Zak's shirt.

Logically, it is most likely a Thunderbird's claw--a very sacred and powerfully symbolic creature to many (usually western) Native American tribes--due to Tsul'Kalu, another Native American-based cryptid, shocking Doc with it in the flashback in the Return of Tsul 'Kalu episode. It is unknown if Zak can use the claw to fire off electricity, like Tsul 'Kalu did during his battle with Doc.