a young man has died after he was stabbed during a violent brawl .
greg gibbins and his friends were at a central coast hotel on sunday night .
the 28-year-old was stabbed and killed outside a pizza store on monday .
his 25-year-old friend was also attacked when he tried to help mr gibbins .
he remains in a serious condition and is expected to undergo surgery .
the offender fled the scene and police have n't found a weapon .
investigations are continuing and police are appealing for any witnesses .