Max von Sydow character is Star Wars: Episode VII is not an ancient Sith Lord or a supernatural being with an awesome voice. He’s a beaten man. He’s old enough to have lived through the Clone Wars, seen the Intergalactic Civil War unfold and then the aftermath of the fall of Emperor Palptaine. He’s no longer a man, he’s a cyborg. His eye is obscured by a ocular viewing device, most likely from a past injury which mean the could no longer use the eye with any ease. One leg is entirely cybernetic now, almost like a Super Battledroid but with metallic claws where his toes would be. He sits at a bar drinking, wary, and old. If you have an oddity, a rare weapon, you might want to bring it to him for evaluation.
Most likely his arm is the arm we were shown in the J.J. Abrams picture with the note card recently.