In the absolute division, Courtney beat his New Zealand teammate to then pit him against a 120kg Olympic wrestling veteran from Palau - eventually succumbing to his opponent's size and power after coming close to submitting him early in the match.
"Although technique is a very important part of competing," he said, "it can be an uphill battle when you are out-sized and out-muscled."
Earlier in the competition, Courtney also secured gold in the under-84kg freestyle wrestling and bronze in the under-84kg Greco-Roman wrestling divisions.
When it comes to the secrets behind Courtney's surprise successes, he says it's just hard work and belief.
"I was really disciplined for months leading up to the tournament. I trained for around three hours a day ... So the training, and believing that I could do well, contributed to my success."
As a result of his wins, Courtney now qualifies for the world championships in Europe later this year, although he may not be able to make it.
"Unfortunately, I probably won't be able to go. Representing New Zealand in less popular sports means that we have to pay our own way, so it's a bit out of my reach," he said.