Ricky William McNamara, 32, approached the Brothers 4 Life founder in the exercise yard used by high-risk prisoners at Goulburn Supermax jail on December 21, 2023.
Both men had been searched in their cells and handcuffed before being brought out to the exercise yard, which was otherwise empty.
As he was being uncuffed, McNamara reached into his pocket and pulled out a shiv, Goulburn District Court was told on Friday.
The convicted killer turned on Hamzy, who was still restrained, and thrust the weapon towards his upper chest and head.
Both men "assumed a fighting stance" and Hamzy blocked the blows with his bound hands and kicked out towards McNamara, the court was told.
The brawl lasted one minute and 40 seconds, and Hamzy's face was cut before corrective officers fired gas into the yard.
McNamara later expressed regret for attempting to shiv Hamzy and explained he had been "overwhelmed with paranoia and worry" at the time.
"My past trauma made me constantly feel threat (sic), and I believed I was going to be attacked," he wrote in a letter of apology read out in court.
"That belief triggered a reaction in me where I acted first to avoid being harmed."
McNamara revealed his tragic upbringing shaped his defensive thinking but he wants to set a better example.
"I've learned to survive by always being on guard," he wrote.
The court was told he has been diagnosed with complex PTSD disorder, substance use disorder and an antisocial personality disorder.
When sentencing McNamara for one count of assault occasioning actual bodily harm, Judge David Barrow noted there was no evidence of any "rational reason" behind the attack.
He found the objective seriousness of the offence was limited, given the short duration of the melee, Hamzy's "spirited and effective resistance", and the minimal injury inflicted.
McNamara was sentenced to a further 12 months behind bars, part of which will be served alongside his current jail term.
He will be 53 years old when his non-parole period ends in August 2046.
Five years were added to his initial 30-year term in 2023 after he tried to behead an alleged child abuser with a knife made out of razor blades, paddle pop sticks and masking tape.
Hamzy meanwhile has been the subject of repeated prison attacks including being punched in the face repeatedly by rival gang member Talal Alameddine during a wild brawl in 2019.
He was also shivved by another inmate in February 2024.
Hamzy has spent the past quarter of a century behind bars since being taken into custody when he was 19 over a fatal shooting on Sydney's Oxford St in 1998.
While in prison, he founded the Brothers 4 Life gang - also known as the Hamzy family - which has been active in Sydney's ongoing gang wars.
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