The verdict came at the end of the second week of proceedings against Adrian Hynd.
At the start of proceedings, the court heard how Mr Forbes had been acting aggressively during a night out at the Windsor Bar.
The court heard how he allegedly spent his final hours alive showing off his ‘gunshot wounds’ before telling a barmaid that he could ‘damage her’, a court was told.
Barmaid Stephanie Ewing,21, said Mr Forbes spent the night of January 1 2017 ‘bothering’ some of the customers who were drinking at the Windsor in Kirkcaldy.
He claimed he was related to a family from Edinburgh called the Kelbies.
The court heard that Mr Forbes was heard telling people in the pub that he was “quite well known in Edinburgh” and that they should search for him on the Internet.
Ms Ewing, who now works as a quantity surveyor, told the court that Mr Forbes unbuttoned his shirt to show off a scar on his stomach to fellow drinkers.
The court heard that Mr Forbes described the scar as being a “gunshot wound”.
And Ms Ewing said that at closing time, he told her that he didn’t want to leave the pub and then asked her a question.
She said: “He said to me ‘do you know who I am? Do you know what I could do to you? I could damage you.”
The court heard that Mr Forbes then met Hynd later in the evening. When the pub closed, Hynd suggested to Forbes and two other men that theygo back to his for a drink.
Offshore worker John Taylor,52, said that he and his brother in law saw Mr Forbes and Hynd having a mock fight as the evening progressed.
Mr Taylor said Mr Forbes had earlier told pub goers that he was “related” to an Edinburgh based gangster and boxing champion, Tyson Fury.
At closing time, Mr Taylor, his relative and Mr Forbes ended up back at Mr Hynd’s home for a “party”.
Mr Taylor said that when he got in, he noticed that Mr Hynd was somebody who “collected” ornamental weapons Star Trek figures and Vodka.
Later in the evening, Mr Forbes, who had spent much of the previous evening talking about boxing, started having a pretend fight with his host.
Mr Taylor told the court: “It was play fighting. Alex took off his shirt and so did Adrian. They were play fighting. They were grappling.
“We thought it was a bit silly and we left.”
After the two men left, Hynd attacked Forbes with an ornamental sword which had a “vampire skull” handle.
Sergeant Alan Stewart,told jurors it was the “worst” scene he had encountered in his entire career.
The officer said he found Forbes in the living room of the house with an ornately handled sword planted deep into his chest.
Sergeant Stewart told the court that the walls, floors, and radiators of the property were covered in blood stains.
He said that Mr Hynd accused of murdering Mr Forbes, was “absolutely covered” in blood.
Sgt Stewart said “I would describe as a scene of utter carnage. There was a male person lying on the floor with a very large knife with a very ornate handle which was very deep into his chest.
“The room was heavily bloodstained. There was blood on the radiators. There was blood on the floors. There was blood on the walls.
“It was probably the worst scene I’ve encountered in all my police career”.
Hynd gave evidence on his own behalf. He claimed that he acted in self defence after Mr Forbes picked up the sword and started attacking him with it.
He said he struggled with Mr Forbes for about 30 minutes.
He said he eventually delivered a “fatal blow” with the weapon moments after his motionless attacker suddenly opened his eyes and bit him on the nose.
He said: “I stabbed him in the side, his left hand side. I thought I’d missed him. I stabbed again, pulled it out.
“Then all of a sudden, it went dead quiet. He never made a move. I thought ‘Will I get up now?’ He wasn’t breathing.
“I moved closer to his face to check and he opened his eyes. He started biting my nose.”
Jurors convicted him of murder. He will be sentenced at the High Court in Glasgow on October 30.