Knight, a father and step-father, was due to be married to his fiancée, Michelle Burke, next month.
She had battled in the charity event earlier that day and won her fight, as did her 10-year-old son, the witness said. The whole family was passionate about boxing, according to Nabby's Boxing Gym which organised the event.
A post on the gym's Facebook page this morning read: "This amazing family have been part of our whanau for two years, three family members fought tonight and they loved the sport. You trained hard Nev, you earned your name the 'Terminator'. RIP."
When Knight collapsed in the ring, Burke was by his side within seconds. "She was doing the breathing for him," the friend said.
Hundreds of people had packed into the Te Rapa Racecourse for the corporate fight night and the crowd was asked to leave the venue over the loud speakers soon after Knight collapsed.
At the start of the fight, Knight, who worked as a linesman for Northpower, "seemed to be holding his own quite well."
Dion McNabney, who owns Nabby's Boxing Gym and trained Knight, told media he was in "magnificent shape" and was one of the fittest men in the gym. He had no known medical conditions and had passed a recent medical examination, clearing him to fight.
It was in the second round when Knight took a hit that knocked him against the ropes, a witness said. When bystanders realised something was wrong, they jumped into the ring and helped Knight on to the floor, placing him in the recovery position.
"Then he went into cardiac arrest," the friend said.
"It looked to me like a medical event," another witness, who also did not want to be named, told the Herald.
"He wasn't actually fighting at the time he collapsed against the rope, went down on the floor and had a couple of spasms and it was all over."
After about half an hour of CPR administered by his fiancée, friends, sparring partners and trainers, Knight was declared dead.
His eldest son, who had also been watching the match, three friends and a police officer carried his body out of the ring, down the stairs and into an awaiting hearse.
"He was a great guy. He was liked by everybody and was a man to be respected and looked up to," the friend said.
About 40 friends, family and colleagues gathered at Nabby's Boxing Gym on Sunday, below where the charity match had taken place for a blessing of the site.
His death would leave a "massive hole" at Nothpower, where he had worked as a supervisor for 10 years, said central region manager Kevin Porteous.
"Everyone is trying to support Michelle as much as possible," Porteous said, adding that they were all "still having their own little struggles as well."
Knight met his fiancée, who is the first woman live line mechanic, at work and they had been together for three years. He leaves behind three children and three step children who will miss him dearly, Porteous said.
"He's going to leave a massive hole in the business. He's the sort of guy when you hand him something to do, he it gets done and doesn't make a big deal about it and just gets onto it and delivers it safely and on time. I just couldn't think of a better guy to have on the team," he said.
Tributes have been flowing in for Knight on Facebook today, with friends and family honouring him as "a great mentor for our young people", a "well respected man" and someone who was always up for a laugh.
Police have referred Knight's death to the coroner.
