Luke Kerrigan selected the largest "katana" blade from his collection of six swords before leaving his house on Grange Crescent, Cundy Cross, Barnsley, and entering his aunt's home nearby, on October 25, 2019, said prosecutor Ian West.
He found her in the living room and told her: "Say owt about your kids again and I'm going to kill and chop everyone up."
"She knows he has a really bad temper," said Mr West, on Wednesday. "She states she had to be very careful about what she said and believes that if she said the wrong thing he would chop her up. She eventually got him to calm down."
As Kerrigan left his aunt's house he smashed the rear window of her Mitsubishi car.
In a victim personal statement, the woman said she believed the situation was caused by family gossip.
She said: "I just wish this had never happened and I don't want him to go to prison."
James Gould, mitigating, said Kerrigan cares for his grandmother, who lives opposite the complainant, and "there have been no further problems."
"This aberration was quickly resolved," he said. “He changed his plea on the same day and there was a long delay for a psychiatric report.”
Kerrigan’s personal problems were compounded by a serious head injury he sustained in 2005, Mr Gould said.
“He can act with some impulsivity,” he said. “He doesn't seek to minimise his conduct.”
Kerrigan, 31, admitted criminal damage and possession of a blade in the magistrates' court, and pleaded guilty to making threats to kill in November, 2019.
Judge Rachael Harrison imposed a restraining order, banning him from contacting his aunt for three years, and told him: “If you bother your aunt in any way shape or form - or someone else does it - you will go to prison.”
She sentenced him to 15 months, suspended for two years, with 20 rehabilitation days and a two-month curfew, from 9pm - 5am.
The swords were forfeited and destroyed, and he was ordered to pay £85 compensation.