Jason Campbell, 27, was sentenced on Friday to three years and nine months in prison for wounding with intent to cause grievous bodily harm.
Judge Mark Callaghan said the "unwarranted and unprovoked" knife attack left a deep wound in the chest of his victim, just missing vital organs.
A second man, Jordon Desmond Bullen, who also had gang ties, received a lesser sentence for his role in July 9 assault.
Campbell and Bullen had gone into the pub's gaming lounge about 9pm. Three men in there were playing the pokie machines. They began interacting, but an argument ensued following some "joking and mocking".
Campbell became visibly riled during the argument and removed the vest he was wearing, turning it inside out to reveal it was a Nomads gang patch.
He then head-butted the victim in the side of the head, before quickly leaving the gaming room.
The victim tried to follow Campbell but he was held back by two friends.
Campbell then pulled out a large knife he had been hiding in his clothing. Holding the knife, he threw a punch aimed at the victim's upper torso but was knocked backwards by a punch to the head from the victim.
He came at him again with the knife, missing the first time but penetrating his chest the second, causing significant bleeding.
Police said the wound was almost 10cm long, and quite deep. The rib cage had stopped the knife entering the inner chest cavity.
Campbell fled from the hotel immediately, but the incident was captured on security cameras.
The victim was stabilised in hospital, and later discharged.
Meanwhile, during the assault Bullen, 24, had been swinging around an extendable baton, and threatened the victim with it.
He was sentenced on Friday for assault with a weapon.
Judge Callaghan said while Bullen had not used the weapon he had used a menacing stance to threaten the stabbing victim, and to keep others away from attacking Campbell.
When Bullen was arrested, police found the baton and a 22. bullet.
Bullen's lawyer said Bullen had distanced himself from the West Coast and his former gang associates and no longer wished to be part of that life.
He was now living in Christchurch and was about to become a father, which was giving him motivation to stay out of trouble.
Judge Callaghan said Bullen did not physically assault anyone but using "menacing" threats justified him being charged with assault with a weapon.
Bullen was sentenced to four months' community detention and nine months' supervision.
It was Bullen's first foray into violent offending, and the victim impact statements related more to the stabbing, the judge said. He took into account Bullen's guilty plea, remorse and background.
Judge Callaghan said Campbell's upbringing had exposed him to drugs and violence at a young age. He had been taking drugs since he was 12 and the gang became his family.
Campbell's lawyer said was now a proud father for the first time and his time in custody had allowed him to reflect on his offending. He wanted a better life for him and his son.
Campbell had offered to meet with his victim and let him know that things had come to an end. However, the victim declined to meet Campbell or update his victim impact statement.
Campbell was also sentenced for stealing petrol, two charges of driving while disqualified, and failing to appear in court. He had 14 previous convictions for driving while disqualified and was disqualified again for 18 months.
