Speaking on Monday, Duncan told the Rutherglen Reformer: “It was a bit strange to wake up and call ourselves champions!
“Over the last couple of years under Gregor, we’ve put in a lot of hard work, and it’s just great we’ve got something to show for it now.
“Last year, we were so close when we got to the final, and it wasn’t a good experience when we lost it. To go one better this year feels very special.
“It’s a great feeling to be part of that team, and making a bit of history for the club. No one would have believed a few years ago there would be a league title trophy for the club, so to be part of that, in a Glasgow jersey, it’s just terrific.”
Playing his part after coming on for the last 14 minutes of the game was a welcome relief for Duncan, who missed the Six Nations campaign earlier this year with an arm injury.
He explained: “When you’re coming back from a long-term injury, you know you have to be patient to get yourself back in.
“It just means when your chance comes, you have to take it. I really wanted to get on and be part of it.
“When we got the last try, we knew that was the final nail in the coffin for Munster, as at that stage they were having quite a lot of possession.
“We scored at a time in the second half when they were putting us under a lot of pressure, but once we got the score, we were far more comfortable for the final few minutes.”