the marsh king had presented his champion with a cloak of flowing silver that rippled on the breeze as the stranger rode , his flank protected in this instance by a hammered shield , enamelled metal whose visible pattern was composed of vertical black and white stripes each four fingers wide ; argent and sable , unknown to jerian the twin hues of the hidden city 's mistress , she of the central keep , the hated mother whose blue five-pointed star radiated from the heart of this monochromatic field .