One thing that I will say is that you should not mount your knife to your leg cause you could loose your leg.

I would not go as far as to say that you would loose you leg. Entanglement hazard...maybe.
Mount it [-]to your BCD or[/-] on a waist belt.
+1
I use a cheap blunted paring knife in a cheap homemade sheath on my waistbelt.
And I wouldn't mount it anywhere that I can't see what I'm doing with the blade. Once, and only once a long time ago, I tried using my knife as a tank-banger to attract someone's attention and ended up cutting something I didn't want to cut while moving it around behind me. Never again.
I used to do that too. My buddy was directly over me (I should have looked up) and I almost got him.