By their name
A person who is missing some fingers on one hand is often referred to as having a partial hand or hand loss condition. They may also be described as having a finger deficiency or digit amputation.
A slight of hand artist.
ambidextrous
Stage hand
Ambidextrous.
Ambidextrous
A person who is missing one hand is often referred to as an amputee or a one-handed individual.
A magician - or conjurer.
a palm reader
Magician/Illusionist
Either Lefty or Left-hander will do.