Leask smashed 50 off just 23 balls to lead defending champions Forfarshire to a seven-wicket win on Sunday.
But Gala did themselves proud after making their first finals day and competing against a number of international players.
Gala captain Josh Irvine won the toss and decided to bat first at Arbroath, who were brilliant hosts for the finals day.
In front of a sizeable Gala support, the Braw Lads got off to a decent start before losing Upul Indrasiri for 13.
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A mix-up between Sid Ponneri and Josh Irvine saw the former run out for five before Irvine and Duncan Millar put together a decent partnership of 31, only for Irvine to be adjudged lbw to Graeme Black.
Gala’s scoring rate slowed despite good knocks by both Millar and Jamie Crooks, both of whom scored 24, and the final score of 104 for six was always going to be difficult to defend.
Forfarshire got off to a blistering start with 13 off the first over but Robbie Irvine then produced an excellent delivery to bowl Scotland cap Craig Wallace for 13.
Rory Johnston and Leask put on further runs before Johnston was dismissed by Dinesh Tharanga, thanks to an excellent catch by Josh Irvine.
And, when Callum Garden fell for two, thanks to another good catch by wicketkeeper Millar off the bowling of Ash Rhode, Forfarshire were 60 for 3, still 45 short of their target.
But Leask and Aman Bailwal (23 not out) took the game out of sight with powerful hitting and excellent running, as the Broughty Ferry side hit their 105 target in the 11th over.
Forfarshire would go on to lose the final later in the day against a strong Carlton side.
Meanwhile, Gala 2nds also lost by seven wickets on Saturday to Edinburgh South 2nds.
Gala posted a disappointing 96 all out, with Robbie Paterson (29) and Jamie Bell (16) top scoring.
In reply, Gala reduced their visitors to three for two but Edinburgh eventually eased to victory in the 27th over. Craig Thomson took all three wickets for 24 runs.