The Hand of Glory is a magical candle, which grants the bearer invisibility, or other powers usually aimed at aiding theft. It is made from the preserved hand of a hanged man, either a candle itself, or holding a candle made from the fat of the same corpse.
From Petit Albert:
Of the hand of glory
Take the right or left hand of a felon who is hanging from a gibbet beside a highway; wrap it in part of a funeral pall and so wrapped squeeze it well. Then put it into an earthenware vessel with zimat, nitre, salt and long peppers, the whole well powdered. Leave it in this vessel for a fortnight, then take it out and expose it to full sunlight during the dog-days until it becomes quite dry. If the sun is not strong enough put it in an oven with fern and vervain. Next make a kind of candle from the fat of a gibbeted felon, virgin wax, sesame, and ponie, and use the Hand of Glory as a candlestick to hold this candle when lighted, and then those in every place into which you go with this baneful instrument shall remain motionless