Ramani Sanderson murdered 21-year-old Shane Mayer when he stabbed him with a sword on the night of July 24, 2019.
At the time of the attack outside Gabba's Bar in Darlaston, Sanderson was on bail for striking a taxi driver with a knife three months earlier in Walsall.
It was one of two incidents where Sanderson was caught carrying a knife before murdering Mr Mayer, Birmingham Crown Court was told.
Shane's father Shaun Mayer, 50, told the Express & Star: "This boy who did this to my son, he already got caught twice with a knife, and they still let him out.
"He was still running around. He should have been in prison, this boy should. My boy would still be alive. The law is not tough enough on this."
In the wake of his son's death, Mr Mayer has called for tougher sentences for those carrying knives and believes police should carry out more stop and searches.
He added: "These people who run around with these knives don't realise what they are doing.
"They haven't just taken my son's life away, they have taken our lives away.
"The law needs to be changed, and it needs to be changed properly.
"Before this happened to Shane, we used to sit and watch the news, horrified that somebody else had got stabbed.
"You never think it is going to happen to you or one of your own."
The fatal attack was sparked by two earlier incidents outside the old Herbert's Park Tavern on Forge Road, with one involving Lewis Green and the other Shane's friend.
Sanderson, 20, was found guilty of murder on Wednesday. Kamron Reid, 20, and Joseph Till, 21, were cleared of murder but found guilty of manslaughter. Green, 21, walked free after being found not guilty of murder.
Shane's father, who lives in Parkfields in Wolverhampton, said his son's death had "ruined all of our lives".
"To them he was nobody, but to us he was our son and her brother," Mr Mayer said.
"You don't have kids to lose them. You never expect to bury your kids.
"His sister has just turned 16, she was 14 when this happened to her brother. We don't like letting her out of the house. It is crazy.
"His sister doesn't like going out anymore because it has scared her. It has ruined her life."
Shane's mother Dawn Bennett, 46, added: "It has ripped the family apart, they don't realise what they have done. We had a perfect family. But not now."
Mr Mayer described Shane as a "brilliant son with a brilliant character and a good sense of humour".
Shane enjoyed fishing and motorbikes, particularly riding dirt bikes, and also playing PlayStation.
He was a popular young man with a lot of friends and enjoyed going on holidays abroad with them. He also loved the family dog Porsha.
Shane had aspirations to become a bricklayer and had job opportunities coming up.
Mr Mayer said: "He would go out of his way for people, he was a good kid."
He labelled his son's killers "scum" and said Shane did nothing to provoke the attackers.
He said: "He never even spoke to them. We have been there [at the trial], we have watched all the CCTV what the police have got. Shane did nothing to nobody."
He thanked West Midlands Police and the prosecutor, Michael Burrows QC, for bringing his son's killers to justice.
He said: "We want to thank the officers that were involved and Shane's barrister for all of their hard work that they have put in, to get this to a trial.
"I know that is their job but they have worked very hard. We would like to thank all the officers that worked on Shane's case and Mr Burrows."
Sanderson, of Walsham Road, near Peckham, London; Reid, of Herberts Park Road, Bloxwich and Till, of Summer Street, Willenhall will be sentenced at a later date.
Lewis Green was cleared of murder but given a three-month sentence after pleading guilty to carrying a hammer earlier in the night. He was released having already served almost a year on remand.