A 20-year-old man accused of cutting off his father’s arm with a samurai sword has had the most serious charge against him dropped, with prosecutors conceding the matter has no reasonable prospect of conviction.

The court previously heard Jaxon Jai Trinidad, 19, used the sword to sever James Nybo’s arm in Kalgoorlie, 600 kilometres east of Perth, in February.

Mr Trinidad was facing four charges, including one charge of aggravated grievous bodily harm and another three relating to possession of a weapon.

The state prosecutor dropped the most serious charge in Kalgoorlie District Court today. 

The court was told the state had no independent eye-witnesses to the incident, and could not negate an argument of self-defence. 

Neither Mr Trinidad or his lawyer were in court for today’s proceedings. 

Mr Trinidad is due back in Kalgoorlie Magistrates Court in December for two remaining counts of possession of a controlled weapon, and one count of carrying or possessing an edged weapon.

A police officer and police cars near a crime scene.

Police outside the Collins Street property in February.  (ABC Goldfields: Robert Koenig-Luck)

‘Reluctant participant’

In February, police prosecutor Senior Constable Matthew Fullgrabe told the court Mr Trinidad heard a commotion towards the front of a property on Collins Street and grabbed a samurai sword he had “recently purchased”.

He said Mr Trinidad unsheathed the sword and was “holding it to scare” his father, who he told to “f*** off”.

The court previously heard Mr Nybo allegedly sent threatening and abusive text messages to his son before the incident.

Mr Trinidad’s defence counsel, Max Crispe, said Mr Nybo was allegedly armed with a baseball bat, which he had raised to strike Mr Trinidad first, when his arm was severed.

The 20-year-old fled the scene and handed himself in to police the next day.

A man smiles after appearing in court.

Jaxon Jai Trinidad, 20, has been on home detention bail since March. (ABC Goldfields: Jarrod Lucas)

Mr Nybo attended Kalgoorlie Health Campus before being flown to Royal Perth Hospital. 

Mr Crispe previously told the court Mr Nybo had not provided a statement to police following the incident.

Magistrate William Yoo earlier labelled Mr Trinidad a “reluctant participant” in the incident.

He was granted home detention bail in March.Â