"He has been affected financially and emotionally," the judge said.
"The victim was simply a parking warden going about his day job."
Emery has an "extensive" list of previous convictions between 2006 and 2016, many of which involved violence. His last violence-related conviction was in 2012.
Judge Davidson said Emery was in a stable, supportive relationship and worked as a self-employed builder.
He completed a 10-week non-violence programme voluntarily after the assault.
He had pleaded guilty to wounding with intent to injure.
Judge Davidson sentenced him to four months of community detention with a curfew of 8pm-6am, nine months of supervision, and 80 hours of community work.
He ordered a reparation payment of $2500.
Outside court, Wellington City Council parking services manager Peter McLellan said they had hoped for a harsher sentence.
"I guess we were expecting a little bit more than community detention, but there really is no winners in a case like this," he said.
The council's key concern was that its people could do their job and go home safely.
"We would have thought there may have been some prison time in there, given the history of the gentleman, however we're philosophical about it. It is what it is. We'll continue to do the job that we're employed to do."
The victim chose not to come to the sentencing because he did not want to relive the experience, and just wanted it to be over, McLellan said.
He returned to his work as a parking warden some time ago and is looking forward to the new year.
The assault follows other reported attacks on parking officers in recent years.
Incidents included an Auckland parking officer being beaten and left with a fractured rib and a partially collapsed lung and another warden in Timaru being shot with a BB gun.