NJ Title 2C - Code of Criminal Justice, specifically; Certain Weapons 2C:39-3, mentions 'any gravity knife, switchblade knife, dirk, dagger, or stiletto'. The key part is 'without any explainable lawful purpose', which makes it very discretionary. Basically, whether a knife is considered a tool or a weapon depends on the circumstances in question. They have added the word 'knife' to 2C:39-5, which is an exemption for carrying a firearm for hunting, target practice, and now a knife for fishing (as long as it's legal, see 2C:39-3), this just increases their discretionary power. If you have a knife on you during the commission of any crime, even if the knife is not involved, it will probably be considered a weapon, then again, so would a baseball bat. Appropriateness is also a big issue with LE here. While there's no specific law against it, walking around in public with a big honkin bowie hanging from your belt, is not going to get the same reaction as seeing you use your SAK to cut the strapping on a box. In most parts of NJ, being discrete is a good idea, not just because of LE, but because of all the sheeple here.