Capes, Couture and Prince William at the Royal Wedding in Jordan

It was the greatest gathering of royals outside of a major coronation: the wedding of Hussein, the crown prince of Jordan, to Rajwa Al Saif. It was also a striking display of the power of modest fashion, as guests including Crown Princess Mary of Denmark, Crown Princess Victoria of Sweden, Princess Beatrice of Britain and various other attendees wore long gowns with airy capes flying off their shoulders, or draped, fluted sleeves, in recognition of Jordanian mores.

Queen Rania wore a high-neck black Dior dress with gold-toned embroidery on the back and at the wrists and throat. Catherine, Princess of Wales, accompanied by her husband, Prince William, had on a similar style in blush pink, with embroidery at the bodice, by the Lebanese designer Elie Saab.

Mr. Saab also made the bride’s wedding gown, a stately sheath with an asymmetric neckline, a draped bodice and what looked like an acres-long overskirt, its grandeur just slightly subverted by the fact that Ms. Al Saif was wearing flat shoes.

Flats! That’s modern monarchy for you (everything being relative). The shoes made for the most unexpected statement of the event, followed only by the gown worn by the first lady, Jill Biden: a light mauve column with a pearl-trimmed keyhole neckline by the Lebanese designer Reem Acra that may have looked startlingly familiar to some.

It was, after all, the same dress Dr. Biden had worn to host the South Korean state dinner just over a month before. Even for a public figure who has made a habit of re-wearing her clothes — and though the choice of designer and style was diplomatically spot-on (more so than at the state dinner) — to appear in the dress twice in such close succession at two major public events guaranteed to yield a photo to go round the world was a pretty radical move.

And one that was impossible to miss. She has pledged her troth, anyway.