A drunk man held a Samurai sword to his mother's throat when she refused to give him car keys.

Cameron Stuart Fergus, 19, of Northwood, pleaded guilty today to threatening behaviour.

He was originally charged with threatening to kill, and assault with a weapon.

In Christchurch District Court today, the assault with a weapon charge was withdrawn and the threatening to kill charge was reduced to threatening behaviour.

On October 10, Fergus was intoxicated so his mother refused to give him car keys, the court heard.

He took a Samurai sword from his bedroom but after a scuffle, he dropped it on a couch.

He phoned someone and told them he would kill his parents, then held the sword to his mother's throat and told her he could do it.

He then forced the sword into the floor. His mother was not injured.

Defence counsel Andrew Bailey said Fergus had no previous convictions and his mother wanted him home.

Fergus would have a forensic psychiatric nurse's report for the next court date, he said.

Judge Philip Moran remanded Fergus to December 13 without entering a conviction.

- © Fairfax NZ News