It looked as though Robson had propelled Wales into a fifth-placed play-off as he crossed for a converted try with 10 minutes remaining, taking his tally to 15 points.
But Scotland stormed back and claimed a try in the dying minutes to snatch the spoils in agonisingly fashion.
Robson was bitterly disappointed with the loss at the Avchala Stadium, particularly as Wales had already defeated their Celtic rivals twice this season, but he is determined to finish his U20s career on a positive note, by beating Italy on Sunday.
He said: “The boys are just absolutely gutted with the end. We must have gone through 10-15 phases and for them to score in the last few minutes is heart-breaking. But it is about being positive, keeping our heads up and going out with a bang against Italy.
“Personally it’s going to be a massive game (against Italy) and I want to finish on a high, it will be the last time I pull on a 20s jersey and I want to make sure I leave everything out there.”
The Dragons pivot was disappointed with his side’s failure to turn pressure into points but they were also on the back-foot for much of the encounter.
For the first time in the tournament, the set-piece failed to fully function, with Wales unable to get a foothold on the game.
Robson added: “We went into it knowing what to expect. In the first half they had the wind and they did well to keep us down in our 22 and we did exactly the same in the second-half but when we had our chances we weren’t as clinical.
“It’s gutting, in the second-half we dominated territory but we let go of a few key chances. We need to be more clinical and once we have scored we need to switch on and hold out.
“But fair play to Scotland, they deserved that. In the last five minutes they put us on our line and they broke us in the end.”
Robson aims to bow out with flourish
Arwel Robson is determined to finish the World Rugby U20 Championship on a high following Tuesday’s devastating defeat to Scotland.