Florida knife laws are very vague
Basically no knife but a ballistic knife is illegal to own.
Just about any knife legal to own is legal to carry openly. I routinely carried a Old Timer Sharpfinger in a sheath or a caping knife in a sheath for years when I was doing the nuisance wildlife job.
I found them to be easier to operate onehanded than a folding pocket knife.
I was never stopped or harassed.
A +common pocket knife" can be carried concealed.
A common pocket knife is basically a 4 inch blade without combat characteristics, whatever that means. And it means just about whatever the cop and DA wants it to mean
If the knife is open and concealed it is a deadly weapon, if it has too many features (serrated blade, lock, hilt guard, finger grip notches it can be considered a deadly weapon).
If you are carrying a knife, even a common pocket knife, while in the commission of a crime it can be considered a deadly weapon.
If the very design of the knife is clearly utility and not harm and has a blade less than 4 inches you are safe to carry without a permit.
These rules have come though examination of past court cases where people were found guilty of concealed deadly weapons on these technicalities