In an otherwise scrappy encounter, the winger was on hand to finish off two good moves to pick up four valuable points for Richard Cockerill’s side in the Guinness PRO14.
Despite being strengthened by some of their returning Scotland internationals, Edinburgh were far from at their best, but still did enough to pick up a win that gives them breathing space from fourth-placed Ulster.
Viliame Mata thought he had given the hosts an early lead after picking up and leaping athletically over the defence at a ruck, but, after lengthy consultation, he saw his effort ruled out due to an infringement at the breakdown.
Despite their early pressure inside the Munster 22, Edinburgh were unable to break through a solid defence and were soon made to pay as the visitors kicked three points to go ahead after 20 minutes.
Both sides struggled for any fluency in attack for the majority of the first half, and it finally took a moment of magic from Dougie Fife to open the game up.
The full-back wriggled free of a couple of defenders halfway inside his own half and raced clear of the line. He looked set for a sensational solo effort only to run out of gas near the 22, but he found the supporting Van der Merwe who ran into the corner for the game’s first try.
Edinburgh were immediately on the front foot after the break after collecting their restart, but, after choosing to turn down three points from out wide, they were held up and failed to add to their advantage before Munster relieved the pressure.
Play resorted back to the midfield struggle of the first period and, after Nathan Fowles was caught at the base of a ruck, Munster forced a penalty to regain the lead through another JJ Hanrahan penalty.
It looked as though Cockerill’s side faced an uphill task to get back into the game after Jason Harries was sin binned for a dangerous tackle, but that sparked their best period of play as they stormed up to the Munster try line.
After going through the phases and seeing one try ruled out, Van der Merwe eventually stepped inside for his second of the evening to put the hosts 12-6 up, despite being down to 14 men.
Cockerill was growing more and more agitated in the stands as Edinburgh attempted to close out the match, but they never came under any serious pressure as they were able to seal a comfortable six-point win.