The Navan Under-17s were up first in the double header and put in a strong second half performance to beat a gritty Bruff side.
It was all square at half-time and with Bruff having missed a penalty in a stiff wind.
Navan got the scoring underway in the second half with a try from Fergal Cleary converted by Eamonn Sheridan.
Bruff pulled it back to 7-7 with a converted try but Navan ran in two more scores to take the game and the trophy on a final scoreline of 17-7.
Conor Burns and Tim Durkan traded early penalties and the Limerick side were 6-3 to the good and gradually grabbed the game by the scruff.
Number 8 Craig McCallum reached over from close range following a lineout to give Shannon/St. Mary's their first try after 33 minutes, with Burns adding the conversion to leave it 11-3 at half-time.
David Evans added another try in the second half and Burns'' conversion made it 18-3. A 50th minute penalty seemed to galvanise Malone but Burns landed another penalty to make it 21-6 late in the game.
A yellow card for Alex McNamara saw Shannon/St. Mary's reduced to 14 men with ten minutes to play and Malone came with their late charge. An enormous drive from their pack lead to a scrum and a quick ball saw Jack McMurty score for Malone.
They kept up the pressure and were rewarded with Gary Andrews' injury-time try to reduce the lead to five points. The young Limerick outfit held out for the remaining minutes to seal the witn and the trophy.