Judge Macdonald sentenced Welsford to 12 months intensive supervision, 150 hours community work and six months' community detention.
The defendant tasted success at 2017's Oceania Wrestling Championships in Tahiti, taking home the gold in the 57kg class and winning each of his contests in less than a minute.
Welsford was also heralded as a talent in mixed martial arts after remaining unbeaten through five bouts in 2015 and winning the New Zealand Amateur International Sport Karate Association bantamweight title.
However, along with the alcohol-fuelled violence, he also made headlines when he was banned from sport for three months after testing positive for synthetic cannabis in 2011.
It appears his combat-sports career may have stalled.
The court heard yesterday Welsford was now a sickness beneficiary and spent 36 hours a week ''gaming''.
On December 31, he was drinking with friends who had congregated outside a house waiting for a ride.
Welsford, holding a bottle of beer, approached a van in which his brother was sitting beside a woman.
The men argued and the defendant repeatedly flicked beer from his bottle at the pair in the vehicle.
But the bottle slipped from his grasp and hit the woman above the eye.
The ''significant cut'' referred to in the police summary, Judge Macdonald said, was ''something of an understatement''.
Defence counsel Andrew Dawson said the injury was unintentional, but the same could not be said about what happened next.
When the victim tried to get out of the van, Welsford slapped her in the face, causing her to fall to the ground.
She suffered swelling, bruising and headaches for some time after, court documents said.
While Welsford claimed to have apologised the next day, the woman was dubious about his remorse and rejected any offer of reparation.
The defendant was convicted of injuring with reckless disregard and assault.
As part of his sentence he will undertake violence, alcohol-and-drug counselling and any other treatment prescribed by Corrections.
