It’s dead ingredients mingle deathiness
“The Hand of Glory is the hand of a man who has been hung, and is prepared in the following manner. Wrap the hand in a piece of winding sheet, drawing it tight so as to squeeze out the little blood which, may remain; then place it in an earthenware vessel with saltpetre, salt, and long pepper, all carefully and thoroughly powdered. Let it remain a fortnight in this pickle till it is well dried, then expose it to the sun in the dog-days till it is completely parched, or, if the sun be not powerful enough, dry it in an oven heated with vervain and fern. Next make a candle with the fat of a hung man, virgin wax, and Lapland sesame. The Hand of Glory is used to hold this candle when it is lighted. Wherever one goes with this contrivance, those it approaches are rendered incapable of motion as though they were dead.”– Notes on the Folk-Lore of the Northern Counties of England and the Borders, by William Henderson.
It’s also believed those knowledgeable in the arcane arts can use a Hand of Glory to open locks and locate concealed treasure. The Whitby Museum possesses a Hand of Glory, it’s the most popular object in the museum’s collection.