Paul John's side saw a narrow 7-5 lead at halftime against Scotland in the semi final of the Bowl overturned as the Scots scored two second half tries to squeak home 17-12.
And while Scotland went on to win the Bowl final 19-14 against Canada, Wales were left to rue over what might have been.
Richie Pugh got Wales off to a good start by scoring in the third minute. Rhys Jones converted but just a minute went by before Scotland hit back through Scott Riddell.
In a tense semi final, both sides kept each other in check until Scotland scored in the fifth minute through substitute Mark Cairns.
Lee Rees levelled the scores at 12-12 with a well taken effort but Scotland had the last word through Struan Dewar to knock Wales out of the tournament.
Earlier in the quarter final, Wales brushed aside Guyana 54-0, scoring seven tries in the process.
It proved one way traffic as Wales led 21-0 at the break thanks to converted tries by Ifan Evans, Adam Thomas and Gareth Davies.
Guyana were outclassed in the second half as Wales raced over for four more tries with Alex Cuthbert, Matthew Morgan (2) and Lee Rees piling on the misery