For CA, you need to just be careful about where you are- there are some city and local ordinances as well as the UC system rules. be very careful that non-concealed is NOT CONCEALED and then don't worry about it. there is not length limit under state law - and a statute of limitations refers to something completely unrelated.
To be safe regarding police "coercive interactions", the honest truth is that you need to LOOK right and ACT right. Looking like a middle class white construction worker is your best bet, you look like you NEED the knife and aren't in a gang or tweaking on meth. Next, don't do it in LA, near LA, or even when thinking about LA.
By and large here in northern CA, if you aren't hispanic and don't dress like a meth-head, you are fine- but the police can be VERY aggressive and completely uncaring about general personal rights if you don't fit the mold.
print out and carry this, with definitions and talking points for explaining:
12020. (a) Any person in this state who does any of the following is punishable by imprisonment in a county jail not exceeding one year or in the state prison:
(1) Manufactures or causes to be manufactured, imports into the state, keeps for sale, or offers or exposes for sale, or who gives, lends, or possesses...any ballistic knife...any nunchaku...any metal knuckles, any belt buckle knife, any leaded cane, any zip gun, any shuriken [ed: "throwing star"]...any lipstick case knife, any cane sword, any shobi-zue, any air gauge knife, any writing pen knife, any metal military practice handgrenade or metal replica handgrenade, or any instrument or weapon of the kind commonly known as a blackjack, slungshot, billy, sandclub, sap, or sandbag. [Ed. Note: this is the paragraph covering "what you cannot own at all" - some of it is downright weird. Plastic/ceramic knives that can go through a metal detector are also banned somewhere in PC12020.]
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(4) Carries concealed upon his or her person any dirk or dagger.
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(24) As used in this section, a "dirk" or "dagger" means a knife or other instrument with or without a handguard that is capable of ready use as a stabbing weapon that may inflict great bodily injury or death. A nonlocking folding knife, a folding knife that is not prohibited by Section 653k, or a pocketknife is capable of ready use as a stabbing weapon that may inflict great bodily injury or death only if the blade of the knife is exposed and locked into position. [Ed. note: so if it's a PC653k-legal knife, and it's carried concealed while folded, it's not "readily available" and therefore doesn't meet the "dirk or dagger definition". ONLY "dirks or daggers" need to be open-carry.]
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25(d) Knives carried in sheaths which are worn openly suspended from the waist of the wearer are not concealed within the meaning of this section.
or just print out the whole website:
http://www.ninehundred.com/~equalccw/knifelaw.html
Jim's pages have been very useful to me in explaining to several fish and game, CHP officers, and park rangers.