They are plasma energy. Which are binded by a specific device to allow constriction of the said plasma energy that sprouts from the body. Allowing it to be focused into the forearm. Inside the gauntlet are numerous recepticles that help guide the plasma energy around to create the rest of the hand and the extras to the arm such as the blades onto it.
Its not exactly hair but its more like sparks flying.
A being of light is not really a mammal or human. If anything is more alien that sort of resembles a human shape. Underneath its armor it is pure energy. Contained in a strong shielding glass that is difficult to break unless sufficient amount of force damages it to make it 'Bleed".