Baelam had a metal left hand. The hand was part of his body and couldn't be removed.
Baelam was an infamous and very successful thief in the Sword Coast until he tried to steal from the wizard Thronthimm Blacksilver. Trying to disable a trap, Baelam lost his left hand. He managed to steal a strange iron golem and fled. However, later the golem animated and tried to kill him but Baelam, using a powerful magic item, destroyed the golem's head.
Afterward, he took the still-working left hand of the golem and went to the wizard Irritym Wonderstar in Waterdeep. Using most of Baelam's, treasure Irritym transplanted the golem hand to Baelam, replacing the lost one.
Impressed by Irritym's result, Baelam decided to train in magic under him. Later, however, Irritym was killed by a group of thieves and Baelam managed to killed the assassins but couldn't resurrect the wizard.
He continued his training in magic, wandering the Sword Coast and killing infamous thieves and using their treasures to finance himself. During this time, Baelam made many enemies, among them the sorcerer Garthagul of Calimport and the infamous thief Ssilban the Silent of Theymarsh.
At last, a large group of thieves attacked Baelam in Waterdeep with the objective of stealing Irritym's remaining magical treasures. Baelam managed to kill all them but destroyed Irritym's house in the process. He then went to Blackstaff Tower and gave Khelben Arunsun all of Irritym's remaining magical treasures, apologizing for the trouble he had caused to the city and then disappeared.
For a time he wandered around the Realms helping innocents and thieving from evil wizards and other thieves. At last, around 1370, he decided to settle in Myth Drannor, with the objective of finding and recovering some lost magic.