The Benin international has netted just 13 goals in 66 matches for the Black Cats and O'Neill has urged to become a more competent scorer which would clearly make him a much more valuable member of O'Neill's side.
"This lad, for the ability he possesses, should score double figures in a season. Into the penalty area, he's beating players and he should do better," said O'Neill.
"He should finish them off, he really should for that ability because he can be mesmeric.
"When he dummies inside to come in, coming across the box, he should just drop the shoulder come inside and have the shot. He does it in training sessions time and time again. That's what I think. He scores in training.
"It's frustrating because this boy could be priceless if he could do that part of the game.
"I always feel that when he gets it wide, of course he'll get a bit tired towards the end of the match and he'll lay one or two off and I don't mind.
"It's when he's got that bit of space and there's miles to go and I'm talking 30 yards outside the penalty area, maybe even less, but when he's taking players on I always fancy him to beat them."