The victim spent three days in hospital and required surgery to remove glass from his head after the incident, which erupted in response to "annoying" noise in a games room.

Offender Varin Hilary Hillbrick, 44, learnt his fate on Wednesday, when he was sentenced in the ACT Magistrates Court to a suspended six-month jail term.

Court documents show the incident occurred in February, when Hillbrick and a friend were playing the poker machines at the Southern Cross Club in Tuggeranong.

The victim, playing a nearby machine, grew annoyed at the pair because they were cheering and high-fiving with every win and screaming with every loss.

Hillbrick's friend and one of the victim's mates later argued about the racket, and a physical fight erupted.

The 44-year-old smashed a beer glass into the victim's head during the altercation, cutting the man and causing him immediate pain.

Hillbrick then kept swinging at the victim, but he did not land any further blows.

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"[The victim] was screaming from the pain, and he ran behind the bar," court documents state.

"He looked back at [Hillbrick], who said, 'Oh f---, I'm so sorry. I don't know why I did this. I've never done this before'."

Hillbrick and his friend left the club before paramedics arrived to take the victim to Canberra Hospital, which he left after three nights with permanent scarring to his forehead and scalp.

Police attended Hillbrick's home to arrest him about an hour after the incident, finding the 44-year-old slurring his words and with a bandaged hand.

In May, he pleaded guilty to a charge of causing grievous bodily harm.

When Hillbrick faced court to be sentenced on Wednesday, defence lawyer Rachel Bird said the offender had been "extremely intoxicated" at the time in question.

She said while the 44-year-old retail manager had intended to hit the victim, he had been so drunk he had not realised he had a beer glass in his hand at the time.

Ms Bird told the court her client had expressed "sincere remorse and contrition", adding that it had been about 20 years since the defendant last committed a crime.

She said Hillbrick, a man held in high regard by "those who know him well", was ordinarily a prosocial person who had once saved someone's life by performing CPR.

Prosecutor Hannah Lee described the attack as "vicious", saying the beer glass had been "rammed" into the victim's face "with sufficient force to break it".

While she accepted that Hillbrick's actions appeared to be "an aberration of character", Ms Lee noted a vulnerable part of the body had been targeted with lifelong consequences.

"The permanent disfigurement [of the victim] is what makes this offence so serious," she said.

Magistrate Jane Campbell noted the victim's scarring started just above his eyes.

"You are extremely fortunate that you didn't get his eye, and that he didn't lose his sight," Ms Campbell told Hillbrick.

The magistrate accepted the offender had not used the glass "as a weapon", saying "it was just something that happened to be in [his] hand" when he impulsively threw a punch.

As a condition of Hillbrick's suspended jail sentence, he must abide by the terms of a good behaviour order for 18 months.

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