Docherty replied that he would rip the man's penis off.
The victim arrived and an argument between himself and Docherty became heated.
According to the summary, the men "got in each other's face" and exchanged words.
Docherty repeated his earlier threat and said he would rip the victim's testicles out.
He then got a 15cm-long hook with a pointed end that had been fashioned out of a round steel rod.
He gripped the hook in his hand and reached down past the victim's groin before pulling the hook up sharply, causing the hook end of the weapon to rip into, and through, the victim's trousers and scrotum.
The victim suffered a torn scrotum that required surgery.
Docherty told police he lost control of his temper in the spur of the moment.
Police are seeking a destruction order for the hook.