The 30-year-old victim had travelled from Te Kuiti for the rugby match, and was taken to Taranaki Base Hospital, however emergency surgery to save his eye was unsuccessful.
At sentencing today, Crown prosecutor Justin Marinovich argued for an outcome of two years and six months' imprisonment.
Marinovich said the injury had a significant effect on the victim, who had just obtained his truck licence, but was now finding it hard to find work.
"It's had a toll on his family and how he deals with anger, for the situation he sees himself in now."
Marinovich said the victim has forgiven Kahu, but that did not mean his life was back to normal.
Defence lawyer Paul Keegan told the court no less than 12 months' home detention was an appropriate outcome for Kahu, who was remorseful for what he had done.
Keegan said there was positive result from a restorative justice conference, where Kahu told the victim he didn't mean to gouge his eye out.
"There are genuine feelings of forgiveness from the victim, it's been a healing event," Keegan said.
A $15,000 doll reparation payment was discussed at the restorative justice conference, and was paid to the victim shortly after.
Keegan said the victim has acknowledged a financial burden was alleviated, and hoped Kahu was not sent to jail or losing a desired career in rugby.
The court heard Kahu intended to use his father's Hamilton house as a home detention address.
The defence concluded by telling Judge Chris Sygrove that Kahu was a changed man after the experience, which now included a successful restorative justice conference, a substantial reparation payment, and Kahu's genuine remorse.
"There is enough there for the court to refrain from imprisoning him, crushing him."
Judge Chris Sygrove recalled arrogance in the defendant during an initial court appearance, but said Kahu was now a more sombre person, who realised his responsibility and was making steps to right their wrongs.
"I don't like sending people as young as you to jail, it's too young and there are too many bad influences," he said.
The judge acknowledged a pre-sentence report indicated Kahu was a low-risk to re-offend, and his father's address was suitable for home detention, before giving his sentence.
Cries from Kahu's supporters in the gallery were heard as a home detention sentence of 12 months was handed down.
Part of the sentence included Kahu receiving his first strike warning.
Outside of New Plymouth District Court, defence lawyer Paul Keegan said the sentence was rare for the type of offending, and the case demonstrated the value of restorative justice, particularly when a conference went well and could be positive for both the victim and defendant.
John Kahu was previously sentenced to 200 hours of community service for his role in the brawl, while Stefan John Hipirini Kahu was convicted and fined $1000.