That fashion staple, the little black dress, has been around longer than you might guess. Philip the Good, Duke of Burgundy, first wore one about 1450 in a bid to set himself apart from the common people wearing colorful clothes. The story behind his landmark sartorial selection is a grand opening for “Royal Style: A History of Aristocratic Fashion Icons” (Prestel) by Luise Wackerl, who has covered royal weddings in Stockholm, London, and Monaco. She deftly weaves fashion facts and faux pas into her text, providing a highly readable accompaniment to dozens of eye-catching images.