The Quins battled hard to hold on and after an even first 29 minutes, Quins captain and fly half Gareth Lewis laned a penalty and the the first try came seven minutes later.
Glynneath full back David Evans was caught and Quins centre Ryan Lovett beat off defenders to score with Lewis converting.
In the second half, Glynneath used the strong wind well, particularly through their young fly half Jack O'Reilly.
It was O'Reilly's clever coss-kick that sent wing Jonny Morgan over after 47 minutes and O'Reilly added the conversion. After 62 minutes, Glynneath were awarded a penalty but as referee Gwyn Morris played advantage, O'Reilly dropped a smart goal.
Glynneath centre Kyle Roberts was unlucky to be red-carded for a second bookable offence, but 14-man Glynneath won it when O'Reilly placed a penalty with eight minutes remaining.
The man of the match award was made by former international referee Cliver Norling who selected the young Glynneath lock Lloyd Bayliss.
The Silver Ball was presented to Glynneath centre and captain Greg Roberts by Mr. Richard Davies, Accounts Manager of Molson Coors.
Maesteg Quins Try: R Lovett. Con: G Lewis. Pen: G Lewis.
Glynneath Try: J Morgan. Con: J O'Reilly. Pen: J O'Reilly. DG: J O'Reilly.