Way back when, English longbow Yeomen would often practice their archery by shooting at a bull's skull. Hitting the eye was considered a great feat of marksmanship.
Another term originated from this activity -- because arrows follow a curved trajectory (due to gravity), and because of the skull's relatively small size, the Yeomen would often be aiming above the skull to hit their mark. However, if they moved close enough, they could aim directly at the skull, or "point at the white," which was referred to as "point blanc" in those times.
(thank you Wiktionary)