I've workedthe county jail here for some years and almost all the cops I know are laid back abouit knives if you are cool.
I think attitude is everything. If your attitude, body language, face, etc. says "cocky, threat, rude,punk, loser, etc." you are gonna get some amount of hassle from the cop. Keep it within legal limits.
I did see a cop book a guy for carrying gravity knife(illegal in WA). It was an 18 year old punk full of attitude. When he frisked him on the street, the cop found one of those cheap copies of the S+W swat knives. The blade FELL OPEN while the cop set it on the hood of the car! Cheap ass knives! He asks the kid where he got such a cheap knife, and the kid tells him to f__k off! He goes ahead and books him for the knife. WE ended up having to do a bit of wrestling with him in the courtroom the next morning, needless to say HE LOST.
PUNKS!!!