Can typically be identified thanks to the attire's characteristics: a red fur trimcape with the Black Knight’s typical black armor, snow piled on the shoulder pads with an icicle or two, and a large white sack held in his left hand.
May be depicted holding his weapon: an axe with a golden handle decorated with a christmas wreath, holly, and red and green ribbons.
Note that it's possible (especially for older artwork), to depict The Black Knight in a winter outfit without it being the one described above, in which case this tag should not be used.
