To answer the question of the backpack- In reference to the concealed carry of fixed-blades, California penal code 21310 specifically says "any person who carries concealed upon the person". My lawyer tells me that what this means is that a "concealed" fixed-blade is only illegal if it is actually on your body, covered by clothing, or disguised in some way so that it doesn't look like a knife. The reason that it isn't illegal to carry a fixed-blade "concealed" in a bag is because carrying it in such a way is not considered to be "readily accessible as a stabbing weapon", and THAT is what makes fixed-blades illegal to carry concealed on ones person. It may seem like a fine hair to split, but that's how the law works. I personally wouldn't be the least bit concerned about carrying a fixed-blade inside a bag.
It should also be noted that the police in California cannot simply search a persons bag whenever they feel like it. The police need either your CONSENT to search you or your property, or they need "reasonable suspicion" to stop you and search you and your property. Like for example, if you happen to match the description of an active criminal suspect reported to be in the area. And if the cops stop and search you without your consent, or if they cannot establish in court to the satisfaction of a judge that they had legitimate "reasonable suspicion" to stop and search you, then not only would any and all charges resulting from the search be thrown out, but you could sue the cop, his department, and the entire county for violation of your fourth amendment rights against unlawful search, seizure, arrest, and detainment.
Bottom line- you have the option of exercising your 4th amendment rights and refuse to give the police consent to search you and your bag. If you evoke this right the police might try to scare you into giving them consent, but that's just a bluff. If they had a legitimate legal right to search your bag then they would, and they wouldn't ask for your permission. Many people give their consent because they are afraid of angering the police, or because they don't know their rights, or because they feel compelled to try and appease the "authority figure". But I say, you have the right to say no, you cannot be punished or arrested for saying no, so if you don't want them to search your bag, exercise your rights as an American citizen and say NO.
Excuse the long post, but I am a big believer in the fourth amendment and like to talk about it's virtues. The fourth amendment is one of the things that protects us from police misconduct and unlawful imprisonment, and makes this a great country.