A robber who mistakenly targeted a banking advice centre instead of a bank and fled with just $5 from a staffer's wallet could face a maximum life sentence, an Adelaide court has heard.

Anthony David McKeough, 31, was armed with a meat cleaver and dressed in a black balaclava and high-vis top when he threatened two employees at a People's Choice Credit Union office at Modbury in Adelaide's north-east.

The robbery occurred on May 28, 2015 and police arrested him the following day at a caravan park in Semaphore.

During his trial, the Adelaide District Court was told one staff member saw McKeough walking towards her office and tried to hold the door shut, but he pushed his way through and demanded cash.

After he was told "it was just an advice centre" and that there was no cash kept on premises, he demanded her purse.

But when she said she did not have it on her, he ransacked her office, stealing a laptop bag with just the charger and an internet dongle inside.

The court heard he threatened another staffer and fled with his wallet, which contained bank cards and about $5.

McKeough was found guilty of two counts of aggravated robbery at trial by judge alone, which carry a maximum sentence of life imprisonment.

He was also found guilty of two counts of dishonestly manipulating a machine after the court heard he had used the stolen bank cards at ATMs at Northpark Shopping Centre shortly after the hold-up.

On Monday, victim impact statements were read to the court from the two employees.

Robbery was 'brazen and terrifying'

One said that the hold-up had "fundamentally changed who she is", and the events of that afternoon replayed in her mind every day.

"It's there when I close my eyes at night, I feel anxious," she said.

"I look twice at everyone, thinking they might be going to do something against me."

Prosecutor Jeff Powell described the robbery as "brazen and terrifying," telling the court that McKeough had not expressed any contrition or remorse or even an acknowledgment of his offending.

The court heard McKeough had a long history of offending, which had escalated in seriousness.

His lawyer, Ben Sale, argued for the sentence to be suspended because his client had reached his 30s, an age where maturity was more likely to transpire outside of prison.

McKeough will be sentenced next month.