A teenager attacked a householder with a tree branch and broke it over his head when the victim came out to confront him for smashing part of his garden wall.
Shane Ward (19) hit the man and threatened to kill him in the incident on a south Dublin street.
He was arrested the next day for repeatedly headbutting a bus stop and damaging it.
Judge Michael Walsh adjourned the cases for the preparation of a probation report.
Ward, of Kimmage Manor, Terenure, pleaded guilty to assault, threatening, abusive and insulting behaviour and criminal damage.
Dublin District Court heard gardai were called to Lorcan O'Toole Park, Kimmage, on September 1.
The occupant was in his house when he heard shouting outside.
When he looked out, Ward, who was with a woman, picked up the stone capping off his wall and proceeded to smash it on the footpath.
The man left his home to confront him and Ward became aggressive, picked up the branch of a tree and hit him on the forehead.Bruising
The branch broke, and Ward picked up another object and said "I know where you live" and threatened to "f**king kill you".
He was located nearby and identified.
The victim suffered bruising to his head but did not require hospital treatment.
Ward was "truly sorry for what occurred", the court heard.
Separately, he admitted causing €225 of damage to a bus shelter on Crumlin Road on September 2. He was seen pacing before headbutting the perspex eight times.
On August 2, gardai saw him walking with a bike at Stanaway Road, Crumlin. He threw it on the ground and fled, but was later arrested and gardai discovered it was stolen.
The accused "simply doesn't know what came over him", his barrister John Griffin said, adding that Ward had been "out of sorts" following the sudden death of an uncle.
Ward "had some alcohol on board" at the time of the assault which may have been a factor.