Florida is not an open carry weapons state. A knife is a weapon. You can get a concealed carry weapons permit which includes knives. They use the word weapons not firearms for that reason.
Weapons in your car, properly cased is ok w/o any permit. Say, in the console or glove compartment.
"...from my cold dead hands" Charlton Heston & NRA
"He which hath no stomach to this fight,/ Let him depart." Henry V
Its the size of the hole & where you put it.