Davros's mechanical hand

Davros' mechanical hand was the artificial, metallic hand with which Davros replaced his right hand.

At the planet Necros, Bostock fired a blaster at Davros' last remaining hand, destroying it and leaving his arm an open flesh wound. (TV: Revelation of the Daleks)

At first Davros had his lost hand replaced by a metal claw which he used for a period of time (COMIC: Emperor of the Daleks!) but later replaced it with this mechanical prosthetic. (AUDIO: The Juggernauts)

The mechanical prothetic appeared like a metallic grey hand except for sharp "nails" at the tip of each finger which mirrored Davros' original hand, and other minor modifications. As Davros gained this hand, he also gained more mobility of his arm allowing him to perform more actions, such as tapping his chair and resting and stretching his arm. (TV: The Stolen Earth/Journey's End, The Magician's Apprentice/The Witch's Familiar)

His hand had the ability to shoot electricity which could harm or kill his enemies, to ward them off if they came close to him. Aboard the Crucible, however, his hand was wirelessly connected to the machinery of the station, and as such it could reverse the electrical shock onto himself. (TV: Journey's End)