kindsa reminds me of the WW2 airborne troopers practice of strapping the full length M3 trench knife on to the ankle (and that's hung out on the "open" and not tucked inside any boot or pants! forget p.c., that's just being practical).
http://www.olive-drab.com/images/knife_m3_legstrapped_175.jpg
(btw, the early leather sheath gerber mark II's also allowed for this ankle lashing.)
nazi jackboots on the other hand afforded a trench knife to be tucked inside of the boot with a spring clip.
here again, as in wartime military practice the knife handle is clearly visible and within easy reach at a moments notice.
traditionally, bavarian hunters and scots have wore knives on the lower leg for ages.
the short dual edge bootknives that came later (as the AG Russell Sting) were targeted for hunters, and not necessarily as covert blade wear (as in the gerber mark I).
which is how short/medium length boot knives are preceived and marketed currently.