This statue of the knight appears on the Five of Cups in The Tarot of Prague deck, and symbolizes loss and bereavement. Fittingly, his legend is a sad one.
One of the less chivalrous knights, Jáchym Berka, who served King John of Luxembourg, often let his jealous rage get the best of him. He was known as the Iron Knight because of his black armor.
He was to get married to a sweet young woman who was devoted and pure of heart. She was the daughter of a blacksmith who made armor and lived at Platnéřská street 119/19, not far from Old Town Square.
The knight had been off to fight some battle in one of the many wars that raged in that era, and when he returned he heard slanderous rumors that his girlfriend had been unfaithful.
The fiancée had been expecting a joyful reunion with her beloved, and was waiting for him on Good Friday. Instead, he showed up with eyes reddened by rage and stabbed her to death. With her last breath, the woman cursed the knight and he turned into stone.
He can be freed from the curse, but only once every hundred years if a virgin pure of heart takes pity on him and gives him a kiss.