Confederate has a point about using a boot knife in public. There's nothing wrong with it around the house or out hunting, if you are dressed to look like it's purposeful.
Boot knives are an old school self defense tool that started in the '70's when Gerber's Mark I became popular in the military. It worked some there, as the combat mentality of the time thought a small last ditch knife concealed in the boot and somewhat accessible had justification. It worked OK, the grip stuck out of the boot top with the bloused pants. The smaller size worked as a utility knife if you didn't mind a dull, blunt cross section and the legal liabilty of two edges.
Clipped pocket folders have far surpassed most boot knife designs. The neck knife with flat cordwrapped handles replaced the boot knife as the fixed blade choice, but the main objection is still availability, which the clip folder excels at, while being more compact and presently made in a much wider variety. The classic boot knife really doesn't offer much in the way of carry options, concealability, or usefulness because of it's inherent design. The sheath is required, and can be bulky in some carry positions - clipped knives are naturally smaller, more compact, and can carry in more places, including bras. Boot knives are always "open," which conveys readiness to respond to danger that the carrier might think is constantly imminent. Folders are carried closed - safe - and have to be turned "on," and then "off," which minimizes their intent as a weapon. It's also a safer carry method, as some fixed blade users have been perforated when they sat on the sheath and the blade cut through into them.
Boot knives are fun, they have a place for some users, but even in the military the folder has the market for it's advantages.
