O'Neill's (pictured) opener arrived just before half-time, when he finished with his left foot from the edge of the box.
Then with 55 minutes on clock, schoolboy Jordan Potter doubled his side's advantage after he fired home from close-range followed a goal-mouth melee.
But it was not all one way traffic, as the Blades hit back with a goal of their own late on to set up a nervy finish for the hosts.
Academy coach Steve Spooner was generally pleased with his side's performance, although he felt they could have added to their scoring tally.
"We started quite slowly with our passing and movement," he said. "But after 15 or 20 minutes we seemed to get out of first gear and started to pass the ball around well and create some good chances.
"In the second half we created several more opportunities and also had a goal ruled out for offside, but when we have the momentum like that I'd really like to see us go for the jugular in terms of goals.
"Having said that it was a good all-round performance and we played a disciplined game without rising to any great heights."