As I understand, what with California's laws being complex,
sheath knives of any kind cannot be concealed unless participating
in a hunting/fishing or similar activity on private or federal
forest land. It being a felony to carry a sheath knife concealed
while in incorporated areas. Folders are okay, and guns only
a misdemeanor in some cases.

I didn't know if size mattered? As a neck knife one would have to carry it outside the shirt?

I was mostly thinking of carrying it in my survival kit in
the glovebox of my car or in my daypack on my way to hiking
etc.