It looks cool on the calf, but if your caught up and you can't bend over and reach it your Sea Hunt special ain't gonna do much good 3 feet away from your hands. But looks way cool.
I have a small 3" UK knife I wear strapped to the inside of my left forearm, a 3 inch blunt tip cheapo strapped to my right shoulder strap, and shears in my BC pocket. Some times I also have a 4" that I wear on the top of my right thigh.
Two quick drills to try out.Think worst case scenario and try to reach different parts of your body with out moving too much (the more you move the worse it gets). If you can't reach it with out bending your leg to 90 degrees and crouching over then its a bad location.
For the next one put a piece of tape over the blade edge to protect yourself and your gear. Seriously, you'll slice yourself if you don't.
Now close your eyes and take out your knife, now put it back without opening your eyes, and without sticking yourself or your suit. Not so easy huh?
Well, when you think about it, chances are if you get caught in something you'll probably disturb everything around you while getting out of it. You might have to save you azz in a blackwater silt out situation. And if its that bad, and getting worse, drop the knife and get out while the gettins good, a knife can be replaced. Even a $120 super Titanium knife ain't worth your life. That's why you carry more than one knife... also why I don't spend more than $25 on any knife, most I've used have been in the $15-$20 range. Cut the line and try to get it back in the holster 2 or 3 times, but after that if you need your hands to get out, just drop it before you stick yourself in the hand or through your dry suit
Been diving for 12 years and had to cut myself out several times (during PSD rescue and recoveries) in blackwater and also have helped others while rec diving. I try to steer around monofilament on wrecks but sometimes its alot easier to just hack it to pieces.
The new spider wire stuff fishermen are using now is really tough stuff. Its much easier to cut with emt shears or good line cutters.