The incident happened at around 11.30pm on Tuesday (29 June) on Cross and Pillary Lane, at the junction with the High Street.
The victim, a 23-year-old man, was walking on Cross and Pillary Lane when an unknown man got out of a red car and approached him, there was a brief exchange before the suspect assaulted the victim.
As the victim walked away, the suspect returned to his car, took out what is believed to be a samurai sword, and threatened the victim with it.
The victim was able to get away and took refuge in a local kebab shop.
The suspect is described as a white boy, aged around 16-years-old, 5ft 11ins tall with a slim build. He had blond curly hair.
Officers investigating have conducted a number of enquiries but are now turning to the public for any information that could assist their investigation.
Were you in the area at around 11.30pm on Tuesday? Perhaps you have dash cam footage of a small red car in the area at the relevant time?
Anyone with information is asked to phone 101 with reference 44210256488.
Alternatively, you can call Crimestoppers 100% anonymously on 0800 555 111.