the royal apparel ... which the king useth to wear - A coat which has been on the back of a king or prince is reckoned a most honorable gift, and is given with great ceremony.
the horse that the king rideth upon - Persia was a country of horses, and the highbred charger that the king rode upon acquired, in the eyes of his venal subjects, a sort of sacredness from that circumstance.
and the crown royal which is set upon his head - either the royal turban, or it may be a tiara, with which, on state processions, the horse’s head was adorned.