I have a friend who is a very recently retired LEO up in the Bay Area. I sent him an email pointing to your OP, and asking him about current California law regarding self-defense, use of force, use of pepper spray, and carrying of knives for non-LEOs, because of my wife's and my pending trip to California in about 11 days. I mentioned my M&P45 and my wife's Kahr, which is why he mentions them in his reply. My friend is very active on the Calguns.net forum where he posts as BigDogAtPlay. He's been a friend of mine for 11 or 12 years now, and he is very much a 2nd Amendment activist. He is pretty knowledgable about what California law permits and forbids, and he is a straight shooter. Please note the parts I highlighted in red!!! For purposes of confidentiality, I've used his and my forum names:
Hi TAM,
The volume limitation on pepper spray for non LEO in California is indeed 2.5 ounces of product, which is the Mark III size. I carried this size for many years on the street as a LEO. Usually these are good for 15 one second bursts, or two - three good hose downs if the agent is a liquid. I tend to prefer liquid over foam but the foam is going to be less injurious to the assailant's eyes are contact range. You can possess as many canisters as you feel you need to, i.e. extras in your luggage.
You can defend yourself from attack, just as happened in the linked story. California law is pretty broad in a less than lethal force scenario. The line gets drawn with the use of a self defense spray in an offensive manner... that becomes an assault and can be charged as high as a felony when that assault is being done to further some other crime.
Knives.... a complete bollocks in California and particularly in and around LA county and LA city. There is no state pre-emption on knives like there is with firearms and local authorities do create a varied web of ordinances. LA city, for instance, bans all folders with a blade over 3 inches. The CRKT M21 blade is 3.875 inches... a problem. LA county bans the open carry of any knife and also bans carry of knives with a blade longer than 3 inches. This is why the responding officer, sympathetically, told the subject of the story to ditch his knife... he was in violation of county ordinances for sure, and may or may not have have been in violation of City of Santa Monica ordinances as well. I can't say because I am not familiar with Santa Monica's ordinances without a bit of research.
State law forbids concealed carry of a fixed blade knife. A lot of the questions you have on knives are going to generally be up to where it is that you happen to be going. I carry a Kershaw Blur assisted opening folder every day, but the blade is just slightly over 3 inches so when I have to travel to LA itself I leave it at home and carry a simple pocket knife with as big a blade as I can muster. Better than nothing. As a LEO I often carried a Ka-Bar #1480 TDI knife, but a citizen can't conceal it in California. I have, on occasion, carried it concealed, but usually just openly on my belt if local laws don't preclude.
It goes without saying that the magazines for your firearms need to have a capacity no greater than 10 rounds. Crossing the state line with assembled mags with a capacity > 10 rounds is a felony. The regular capacity for an M&P 45 is ten and the Kahr is seven so no worries there if you have OEM magazines for them. Locked container carry here, your mags can be loaded but not inserted into the gun, chambers must be empty, loaded mags can be in the same locked container with the gun. You can keep loaded and concealed firearms in your temporary domicile (i.e. hotel room) under an exemption in the Penal Code, so it's okay to load up when you reach your room for the night.
I don't discount the story of your friend, but for an assistant district attorney (Santa Monica does have it's own branch courthouse) to come rolling out on that type of a call is absolutely assinine. There was no reason for him to do that unless they are totally bored. I've seen several dozen similar calls in my time and we settled each and every one of them without an ADA having to come out and hold our hands. I'd be willing to bet he doesn't have a lot of respect from the field personnel.
Let me know if I've left anything unanswered. Have a happy new year and enjoy your trip.
BigDogAtPlay