When a drunk neighbour came over and started touching his sleeping mother, a 5-year-old boy ran downstairs and grabbed a knife.
The Dunedin District Court heard this week that Mosgiel's Gareth John Macmillan snatched at the blade as the child passed it to his mother but the utensil was ultimately not used by either party.
The 45-year-old defendant fled the address when the woman tried to call her friend.
Macmillan pleaded guilty to assaulting a female and being unlawfully in a building after the November 25 incident.
The victim said the ordeal had "ruined her life" and she had to move from the house because she no longer felt safe there.