Most of the laws discussed for NYC are the STATE laws that are being enforced. In NYS, you can not carry ANYTHING with the intent to use it as a weapon. Legal knives carried with the intent to be used as a weapon would then be considered "dangerous knives" and would be illegal. NYS Penal Law bans switchblades and gravity knives ( in most cases), but there are not too many other restrictions. Knives designed solely for use as a weapon are considered dangerous knives. NYC goes after any locking knife that can be flicked open ( often with unreasonable force) to be considered a gravity knife, but other parts of NYS do not go to that extreme ( but they could as this is state law NYC is enforcing and there is case law to back up their actions).