"He just punched him, he didn't punch him hard," he told the court.
While Taine Tipene chased someone towards the Grey Lynn shops, he said, he lost sight of his cousin.
Moments later he found Luke Tipene on the corner of Coleridge St, bleeding profusely from a wound to the neck.
"He wasn't good," Taine Tipene said.
"We tried to block all his blood from coming out."
Luke Tipene died in Auckland Hospital about four hours later.
Under cross-examination, the witness denied they had gone to the party to fight.
"No I didn't, neither of us did," Taine Tipene said.
"Our intentions weren't to back [our friend] up, our intentions were to pick him up."
Crown prosecutor Brian Dickey told the jury Skeen became "enraged" after the victim had punched him, and sought retribution, allegedly finding a beer bottle in the back of a ute and smashing it to form a "protruding, jagged blade".
There were at least seven blows with the weapon, according to the Crown, one of which caused a 12cm wound, which stopped just short of Tipene's spine and pierced his jugular vein.
Yesterday Togiavalu, 20, broke down in court as she recounted the sound of a beer bottle smashing on concrete.
Skeen began swinging at Tipene with the shard of glass as the victim backed off with his hands up, attempting to defuse the situation, she said.
"Then the bottle went into Luke's throat."
Togiavalu and her cousin retreated to the roadside as the melee subsided.
"I was a little bit in front of him and I turned around and he dropped his hands and all the blood started squirting out of his neck," she said.
"He was whispering the word 'ambulance' and I started screaming for help. I was just sitting there holding him, trying to stop the blood."
Defence counsel Lorraine Smith said her client, who was 16 at the time, may be guilty of manslaughter but lacked the requisite intent to be convicted of the more serious charge.
"The Crown will have to prove beyond reasonable doubt that Skeen, swinging out with a broken bottle, turned his mind to the fact that what he was about to do might well kill and he decided to take the risk regardless. The defence says that's simply not the case," she said.
It is the second trial for Skeen, after a jury failed to reach a verdict last year.
The trial continues.