32 year old Viet Nguyen entered Pretty Nails in Church Street in June and produced what was believed to be a silver handgun.
He pointed the imitation gun at a member of staff whilst shouting in Vietnamese.
The suspect then tried to grab the member of staff, however he was held back by other staff members.
Nguyen pleaded guilty to a number of offences including possession of a firearm with intent to cause fear of violence.
He was sentenced to 18 months in prison, suspended for two years.
An order for deprivation of the weapons and destruction of drugs was also ordered.