The opener blazed an unbeaten 48-ball 75, which included 11 fours and two sixes, as the hosts cruised to the 126-run victory target at Willowmoore Park with just under 5 overs to spare.
Cipriani came on top in a shortlist that also featured Exeter's Henry Slade and Santiago Cordero, Sale scrum-half Faf de Klerk and Northampton half-back Cobus Reinach.
The 37-year-old Williams is still waiting for a record-equalling 24th Grand Slam triumph, with her last victory coming at the 2017 Australian Open shortly before taking a break from the sport due to pregnancy.
With the increasing similarity in the way teams approach the two formats of the white-ball game, there seems no reason why the West Indies cannot again be a force in 50-over cricket as well.
Guinea midfielder Keita sustained an adductor injury in Liverpool’s 3-0 semifinal first leg defeat at Barcelona this month and was ruled out for two months, meaning he would likely miss the African Cup of Nations in June.
On a dry and hazy morning in the Mediterranean principality, the cramped harbourside paddock was in sombre mood as Formula One honoured the Austrian, who died overnight Monday aged 70.
The striker said Monday he was quitting the national team after he was angered by coach Kwasi Appiah's plan to strip him of the captaincy for next month's finals in Egypt.