A slash hook was produced during a serious altercation on Upper John Street, Kilkenny in the early hours of Sunday morning.
Between four and five people were involved in the incident which gardai are treating very seriously.
The implement produced was later recovered at the scene by investigating officers. There were no serious injuries reported.
Gardaí want to speak to anyone who was in the area at the time. They are asked to contact Kilkenny Garda station on 056-7775000 in the strictest confidence.