The complexion of the game changed in the 12th minute of the second half when Marist centre midfielder Josh Murphy collected a deflection off the left upright to slot the ball past a gallant Hibs goalkeeper, Reece Huffam.
Part-time keeper Huffam had denied Marist a goal just three minutes into the second spell when he dived to his right to parry a penalty kick from Jett Hogg, whose body lingo made it too obvious.
The 1-0 lead had stung Hibernian into action as coach Jac Kitt reshuffled the back line to three and urged players to switch to attack mode.
Hibs striker Mark Foote minutes later clipped the upright before captain/midfielder Damian Gregory rattled the crossbar with a 25m speculator but Marist, with former Bay United player Matt Hastings and Napier City Rovers guest player Daniel Ball, hung on for victory.
"It was hard because if they had nicked one [goal] they would have sat behind the ball," Dunning said of their bunker mood.
"We had to score but we panicked a little bit after having done well all weekend," he said, adding his Reuben Thirston-captained side were well-deserved winners who could have scored several goals.
It was a good workout for many of the Marist youngsters who will turn out again on Tuesday with the Hawke's Bay United franchise youth team.
Dunning was resigned to losing several players to university next season but, while it was a pleasure to work with them, he was comfortable in the knowledge that he had stocks to step up to the Pacific Premiership grade.
Hastings, who also was his assistant, has moved to Gisborne.
Marist also will compete in the satellite squad of the Napier City Rovers Under-19 tourney at the same venue next month.
Kitt was proud of the way his division one men battled against a premier side.
"Our guys have punched above their weight all season so we're really pleased. Maybe if we'd won the final we would have been happier but it's just been an awesome season," he said with a laugh.
Palmerston North Marist Firsts beat last year's winners, Birkenhead United, 2-0 to claim the women's open crown.
Wellington Skavs won the Masters men's grade on a two-goal average after they were equal on points with Hibernian.
In the men's social grade, PN Marist Banshees beat Napier Marist (Div 2) 3-1 in the final.
In the women's social grade final, PN Mysteries beat PN Evergreenz on penalty kicks.
Rovers Central League assistant coach Chris Greatholder picked two paper tourney teams for open grades:
Men: Mile Seddon, Conor Boyd, Ben Crane, (Marist Wellington); David Morton, Josh Sansom (Marist Wee-Ones); Jake Murphy, Dave Ellison (Napier Div 1); Reuben Thurston, Jett Hogg, Josh Murphy, Ben Lack, Dillon Du Ross (Napier Marist); Mark Foote, Luke Woon (Hibernian Div 1); GK Wilson McCullough (Napier Marist).
Women: Karla mason, Maeghan Donnelly, Sarah Taylor, Sharne Crous, Paige Cook (Birko Fight Club); Tee-Jay Lynne-Lewis, Hannah Fitzgerald, Mikaela Boxall, Molly Woodhead, Brooke Argyle, Laura Nottle (PN Marist First); Jess Robertson (PN Evergreenz); Hollie Murrell, GK Mandy Owen (Gisborne Ladies); GK Kelly Rangi (Hibernian First).
