Finn Colclough has had his sentence for manslaughter reduced to eight years after an appeal court ruled his offer of a guilty plea should have been considered by the trial judge.
Colclough, 19, of Waterloo Road in Ballsbridge was found not guilty of murder but guilty of the manslaughter of 18-year-old Sean Nolan in May 2007.
Mr Nolan had been out celebrating his graduation from secondary school when he and friends stopped outside Colclough's house.
Colclough, who was also celebrating that night, came out brandishing kitchen knives and Mr Nolan was stabbed to death.
Colclough was charged with murder but was found guilty of manslaughter.
He appealed his ten-year sentence and today the Court of Criminal Appeal reduced that sentence by suspending the final two years.
The three-judge court said his offer to plead guilty to manslaughter before the trial should have been taken into account by the trial judge.
Afterwards, the victim's mother, Charlotte Nolan, said she was relieved the legal process was over and said the ten-year sentence imposed by Mr Justice Paul Carney still stood.
However, she called for urgent changes in legislation to tackle what she called the 'epidemic of knife crime'.
