Lisa Hartshorn had been staying with Mark Woodward following her split with Creswell man Ian Foreman.
She heard Woodward bragging he had stabbed a man some weeks earlier. He had two knives with seven and five-inch blades and rubbed them together.
Helen Griffiths, prosecuting, told Chesterfield magistrates Ms Hartshorn felt scared and called Mr Foreman to ask if she could go back to him.
She called a taxi and Woodward, 32, said he was going with her and would stab Mr Foreman.
The driver called police after seeing Woodward had a knife and dropping the pair in Welbeck Street.
“She told Mr Foreman the defendant had a knife. He was holding one in each hand and stood in a threatening way.”
“Mr Foreman grabbed two bigger knives from the kitchen and said: ‘Mine are bigger than yours. You have got to get past me and my dog’,” said Mrs Griffiths. Woodward then put his knives down.
He was arrested and told police Ms Hartshorn had asked him to go with her to Mr Foreman’s home to collect some clothes.
He alleged Mr Foreman said to him: “Come on down big boy and I’ll kill you” and he only took the knives as a deterrent.
Woodward, of Pretoria Street, Shuttlewood, admitted possessing blades in public on 22nd November. He had previous convictions for wounding and disorder.
Magistrates committed him to be sentenced by a judge at Derby Crown Court on 6th January.
Defending, Steve Brint said he had suffered chronic alcoholism for years.