Fly half Henry Slade added 13 points with the boot, while wing Jack Nowell also crossed the whitewash with Wales fly half Sam Davies keeping the hosts in the contest throughout with five penalties.
And for Hunter, who was overseeing his last match in charge of the Under-20s before he heads to the Exeter Chiefs, believes the work ethic of his players was key to their success.
"It's a massive achievement and the guys deserve all the credit," he said.
"They're a hard working group and this trophy is their reward for the work that they have put in.
"Wales gave it a real go and full credit to them, we never felt comfortable."
Captain Jack Clifford added: "I'm so happy for all of the boys and all of the management, everyone works so hard and to end up with this trophy as captain is a dream come true.
"Massive credit to the Welsh though, at no point did we feel like the game was won until the final whistle blew."