The King of Swords sits enthroned in Pamela Colman Smith's picture, an upright sword in one hand, robed in the pale blue Waite associated with clear thought, against a sky of thin high clouds; butterflies and a single bird carved into his throne are usually read as symbols of transformation and elevated intellect, details Smith also used, in varied form, on the Queen of Swords' throne.
The Golden Dawn and Thoth court restructuring affects this card more visibly than most, since Crowley and Harris's system has no King at all: their Knight, Queen, Prince, Princess scheme puts the mounted Knight of Swords, not a seated king, at the head of the suit, and what Waite calls the King corresponds most closely to their seated Prince, shown enthroned in a chariot rather than on a static throne. A reader moving between the two systems needs to track this substitution carefully, since the names King and Knight point to genuinely different ranks depending on which deck is in front of them.
The Marseille Roi d'Epee, like all four Marseille kings, is a static heraldic figure holding the suit emblem with none of Smith's added symbolism; the butterflies, the bird and the specific coloring are Rider-Waite-Smith contributions with no older precedent, part of the considerably richer visual vocabulary Smith brought to the court cards generally, not only to the numbered pips.