Katen Kyoukotsu manifests as two distinct women. The first is a tall purple-haired figure with a red ribbon around her neck and an eye patch over her right eye. She's got this whole oiran aesthetic going—the high-class courtesan vibe—with a dark flowing dress that shows off her cleavage, an indigo cape decorated with a skull, and a golden bone headdress. The second form appears later and is much more understated, dressed in dark, fitted clothing. Over time with Shunsui, Katen Kyoukotsu has grown bored, openly dismissing his nature as dull.
What makes this zanpakutō stand out is that it's actually two separate swords—a proper daisho pair. When released, they transform into a matching set of large falchion-like blades. The weapon can manipulate wind, and Shunsui's got at least two known techniques: "Bushō-Goma" (Lazy Isolation), which fires a wind blast meant to throw an opponent off-balance, and "Takaoni" (Mountain Demon). That second one never got properly demonstrated since Starrk interrupted it with his cero, so its full capabilities remain a mystery.
His bankai is unrevealed, though Ukitake pointedly warned him never to use it around so many witnesses—which tells you it's probably something he'd rather keep under wraps.
Content compiled by AnimeList.moe from publicly available sources.