Bronx and Banco Runway Piece

This is a Bronx and Banco worn on the runway piece. I’m not sure if it’s a cape or a high waisted open front high low skirt. It does feature a gathered top half which opens in middle and has a flowy train like flow. I would wear as a strapless cape maxi dress cute Bodycon dress under but it was too tight/small on the bust for me. But it’s an authentic worn on the runway piece.