A legendary ranger of the Night’s Watch, once well-acquainted with Mance Rayder before Rayder deserted the Watch, Qhorin has his byname “Halfhand” from the fact that part of his hand was cut off when a wildling disarmed him and struck at him with his ax—to save himself he used his hand to catch the weapon, and then allegedly thrust the bleeding remnant into the eyes of the wildling to blind him long enough to kill him. He learned to use his sword with his left hand after that, and it’s said that he became even more proficient with that hand than he had been with his right. A big man, tall and straight-backed, his hair is long and graying, and the garments he wears are faded almost to gray.
The actor cast in the role is about the right age (and his face is rather spot on!) but he is of average height (and, of course, is not lacking any fingers that we know of).