WA murder victim's mum cries every day

The mother of a Perth man who was murdered at a 21st birthday party with a pair of scissors says she still cries every day over the pain of her loss.

Jamie Devine, 20, died in hospital after Ashley James Gunson, 24, stabbed him in the heart in January last year.

Gunson appeared in the West Australian Supreme Court on Monday for sentencing submissions.

In her victim impact statement, Mr Devine's mother, Pauline, said her heart still ached knowing she would never hug her son again.

"I have no idea how I'm supposed to live the rest of my life without him," she said.

"He touched the hearts of many people.

"There is a huge, empty space in our lives that will never be filled."

Ms Devine said her son, a young father, had been looking forward to celebrating his own 21st birthday weeks after the party.

"Jamie was not perfect, but he was sure striving to be," she said.

"I still cry every day. I know what has happened but I still find it hard to accept."

Ms Devine said she felt like she was on a roller-coaster where she felt OK one moment but then would fall into a heap and become a "sobbing mess".

Defence lawyer John Bougher told the trial that a drunk and drug-affected Gunson did not intend to kill Mr Devine, and said on Monday that there was no premeditation.

Gunson, who was also found guilty of unlawfully wounding Brodie Brouns during the same altercation, but was acquitted of the unlawful wounding of Karl Viandante, will be sentenced later this week.