Don't what a pick lock blade is, but under TX law any thing single edged and under 5-1/2 inches is legal to carry, concealed or open. If it's single edged but 5-1/2 inches or longer, it is illegal to carrry in public.
The only knives illegal to carry based on "type" regardless of blade length are daggers, dirks, poniards and bowies. The first 3 are all double edged, so they are easy to identify, as far as LEOs are concerned.
The only nebulous thing is the bowie. What constitutes a bowie has never been defined. A clip point knife of any length with a sharpened swedge is considered by many to be a bowie. A butcher knife could be considered a bowie. Many consider a knife with a double guard is a bowie, although the original only had a half guard. I wish we could at least get the nebulous term bowie removed from the law. Maybe someday.