My understanding of Los Angeles knife laws is as follows-
You can carry a folder of any size as long as it is conceald.
You can carry a folder in "plain view" if it has a blade under 3 inches.
Carrying a folder clipped to your pocket is considered "plain view" and is illegal if the blade is 3 inches or longer.
You can openly carry a fixed-blade if the blade is less than 3 inches.
Carrying a fixed-blade with a blade 3 inches or longer in "plain view" is illegal.
Carrying ANY fixed-blade conceald on your person is illegal under CA state law no matter where you are in the state.
I live in San Diego and checked LA laws because I was going there once for work.
Of course, I'm just some guy on the internet. So take this post for what it is.