Does Hexblade lvl14 allow one additional use per short rest, or does it allow unlimited uses between rests?

@JeremyECrawfordMr. Crawford, may I inquire about Hexblade’s lv14 Master of Hexes? Does it allow one additional use per short rest, or does it allow unlimited uses between rests?

— John Appleton (@jaa0109) February 23, 2017

@jaa0109But only one Cursed target at a time, yes? That's what it says, yes.

— Jeremy Crawford (@JeremyECrawford) February 23, 2017