Despite dropping games in each of the rounds leading to the climax, second seed Duncalf was in stunning form in the final - despatching world number three Grinham, who was competing in the 50th Tour final of her career, in just 33 minutes.
The victory comes just seven days after the England number one went down in the opening match against Egypt in the final of the Women's World Team Championships in Cairo - only to see the hosts go on to wrest the title from England in front of an ecstatic home crowd at the National Stadium.
The 26-year-old from Harrogate in Yorkshire was delighted with her performance in the inaugural WISPA event on the Egyptian Red Sea coast: "It was a great new tournament in a lovely setting and I was happy with how I played," said the world number six after winning the fourth Tour title of her career.
Semi-finals:
[1] Rachael Grinham (AUS) bt [3] Omneya Abdel Kawy (EGY) 13-11, 11-6, 11-9
[2] Jenny Duncalf (ENG) bt [4] Shelley Kitchen (NZL) 3-11, 11-6, 11-5, 11-9
Quarter-finals:
[1] Rachael Grinham (AUS) bt [5] Jaclyn Hawkes (NZL) 11-9, 9-11, 11-9, 7-11, 11-6
[3] Omneya Abdel Kawy (EGY) bt [6] Lauren Briggs (ENG) 11-3, 6-11, 4-11, 11-9, 11-7
[4] Shelley Kitchen (NZL) bt [8] Dominique Lloyd-Walter (ENG) 12-10, 11-6, 11-9
[2] Jenny Duncalf (ENG) bt [7] Raneem El Weleily (EGY) 7-11, 11-9, 11-3, 11-5
1st round:
[1] Rachael Grinham (AUS) bt Joelle King (NZL) 9-11, 15-13, 11-5, 11-2
[5] Jaclyn Hawkes (NZL) bt [Q] Nour El Tayeb (EGY) 11-3, 11-7, 11-3
[3] Omneya Abdel Kawy (EGY) bt [Q] Tara Mullins (CAN) 11-5, 11-3, 11-4
[6] Lauren Briggs (ENG) bt [Q] Sara El Noamany (EGY) 11-6, 11-2, 11-3
[8] Dominique Lloyd-Walter (ENG) bt Louise Crome (NZL) 11-5, 7-11, 9-11, 11-8, 13-11
[4] Shelley Kitchen (NZL) bt [Q] Heba El Torky (EGY) 11-8, 11-6, 11-6
[7] Raneem El Weleily (EGY) bt Orla Noom (NED) 11-8, 11-5, 11-1
[2] Jenny Duncalf (ENG) bt Amelia Pittock (AUS) 6-11, 11-2, 11-9, 11-7
Issued by iSPORTmedia