One person was arrested and charged with assault and weapon possession.
Police said they received a call about the altercation at approximately 12:50 a.m.
Investigators determined the confrontation began between two adult men on board the train and escalated into the slashing.
The victim suffered non-life-threatening injuries and refused medical attention, police said.
The other man was arrested for assault and possession of a weapon. NJ Transit Police are leading the investigation.
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