JAILING a rehabilitated young man two years after he slashed Wagga real estate agent Kerry Flinn with a knife would undo all the good that has been achieved since then, a judge has said.

Judge Jennifer English made the remark while sentencing 21-year-old Laurence Harry Egan in Wagga District Court.

Egan appeared for sentencing after pleading guilty in Wagga Local Court on August 28 to two charges: assault with intent to rob while armed with an offensive weapon and assault occasioning actual bodily harm.

Egan was a 19-year-old cannabis and amphetamine user on September 5, 2012, when he bailed up another young man in the Franklin's Supermarket car park off Peter Street.

Egan put his arm around his victim and said "we are going for a walk" before pulling out a knife with a 10cm blade and demanding the other man's mobile telephone.

The victim started to struggle and was punched in the face.

At this point, Mr Flinn saw the fight and stepped in to break it up.

Egan swung his hand that held the knife and Mr Flinn's left hand was slashed.

Egan, who had been living on Fox Street, then ran off.

He fled to Shepparton and then moved to Echuca where he was eventually tracked down by police in April this year and arrested.

The court heard Egan began using cannabis when he was 15 and amphetamine when he was 16.

By the time of the offence his weight had dropped from 80 kilograms to 45kg.

The day before the attack, Egan consumed cannabis and amphetamine but also sought help for his drug addiction from a doctor that day and was prescribed valium.

"He was coming down from drugs and he was taking valium, which can't be good for him," Egan's solicitor David Barron told Judge English.

Giving evidence in the witness box, Egan said that after leaving Wagga he made contact with his family again and with their help received mental health, drug and alcohol counselling and began work on piggeries in the Echuca area.

He said he was drug free and hoped to resume a painting apprenticeship.

Mr Barron asked Egan if he understood how frightening his attack would have been on the young man and Mr Flinn.

"Yes," Egan replied.

"I'm very sorry for what I did. I don't think I intended to hurt anyone."

Mr Barron asked Egan what stopped him from taking drugs now.

"Just everything it has done to me and everything I have screwed up because of drugs," Egan replied.

Judge English gave Egan an 18-month suspended jail sentence for his attack on the young man and a nine-month suspended sentence for the attack on Mr Flinn.

She said she did not want to send him to jail, a place she called the "university of crime", and on this occasion rehabilitation as a sentencing factor was above general deterrence.

"To put him in full-time custody would undo all the good that has been achieved," Judge English said.

"I find he is remorseful and contrite, has excellent prospects of rehabilitation and unlikely to reoffend."

But she warned Egan not to re-offend during the next 18 months.

"If you break these bonds and let me down you will be brought back before me and I will revoke the bonds and you will be sent to jail," Judge English told Egan.