The pair's respective families packed the ACT Supreme Court on Thursday as Justice Michael Elkaim ordered that Kerry Kourpanidis serve at least three years and nine months behind bars for the manslaughter of Warren Hordpenko.

The two tradesmen were strangers until a fateful evening at the south Canberra pub last July.

Kourpanidis was there having dinner with his family when Mr Hordpenko, who was in the area for work, drunkenly touched the local man's daughter on the face and remarked that it had many "perfect" features.

"But I can tell you one thing I hate about you," Mr Hordpenko told Kourpanidis' six-year-old girl. "I hate your nostrils."

Kourpanidis and his stunned family quickly left the hotel, with his daughter saying on the drive back to their Griffith home that she was "going to have nightmares about that man".

After putting the confused girl to bed Kourpanidis was confronted by his girlfriend, who tearfully criticised him for not stepping in to stop Mr Hordpenko.

Kourpanidis' girlfriend told him she wanted to go back to the pub to give Mr Hordpenko a letter about his bad behaviour, but Kourpanidis insisted he would deal with it.

The now 36-year-old assailant then drove the short distance to the hotel and went back in for less than a minute, tackling the 44-year-old victim off a bar stool as he raged: "You f---ed with my daughter, c---".

Mr Hordpenko did not try to fight back as Kourpanidis repeatedly punched him on the ground, with one blow causing the victim's head to smash against a wall.

Justice Elkaim said exactly which part of the attack caused Mr Hordpenko's death was unclear, with a forensic pathologist finding "a sudden movement of the head" during the incident had likely caused an artery to tear.

"It is to be recalled this was a short ... vicious attack, which resulted in a death," the judge said.

"Absent the identification of a cause attributable to a specific action, the only logical approach is to regard the attack as having caused the death."

The court had heard earlier on Thursday from many people who knew the men.

The victim's widow, Christine Henderson-Hordpenko, fought through tears as she said her soulmate "Wazza" was "one of a kind" and "the most beautiful man".

She said they had planned to start a business together on a small island in the Philippines.

"My life was so full," she said.

"I had an exciting future with Wazza and, as quickly as that, [Kourpanidis] snuffed it out. [He] took my man, my protector, my heart, provider, the love of my life.

"Who will kiss me, cuddle me, comfort me, protect me and love me the way you did, Wazza? You will always be my one and only."

Mr Hordpenko's father Robert detailed how his "supposed golden years" had "turned to hell", while the victim's mother Robyn said the "stupid" attack had "sentenced me to a broken heart for the rest of my life".

A string of people also gave evidence in support of Kourpanidis, describing him as a doting dad and "a good man who made a mistake".

"Ultimately I am dealing with the tragic tale of two decent men, but one of whom killed the other and must be appropriately punished," Justice Elkaim said.

The judge said it was crucial for Kourpanidis to be held accountable because "the public must know that unjustified attacks can have severe consequences".

He said Kourpanidis had been sober and had "ample time for reflection" before returning to the pub to launch the fatal assault without any attempt to speak to Mr Hordpenko first.

"While I would not necessarily use the word 'cowardly', the assault was upon a person taken by surprise and involved not only the initial tackle but also the continued striking of the deceased to his head and body," Justice Elkaim said.

"Although the attack was short, it was brutal and included the targeting of the deceased's head."

The crowded courtroom stayed mostly silent as the judge pronounced Kourpanidis' sentence, but one woman began crying hysterically.

With time already served, Kourpanidis will become eligible for parole in April 2024.

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