When I first began diving in the early 80's, every guy in my OW class bought their basic gear, mask, snorkel, fins, boots, BFK. You know, the normal manly basic gear. Got out of diving in the late 80's, came back last year with a few friends who got certified the year before, 100 dives each when I started back up with them. First time I dove with them, gearing up, there they go with the basic gear suit-up, strapping their BFK's to their calves. So guys are still buying the basic gear, which still includes BFK's. I asked if they had EVER used them. Nope. Ever think of carrying shears instead? Have those too, but we only bring the knives. Whatever. I just have a small crappy stainless, half rusty BC knife attached to my inflator hose. I should grab those extra shears my buddies have lying around when they are not looking.
In the 80's I used to carry an abalone iron instead of a knife. Very good for holding off of things, prying, poking, smashing, just not cutting. I should have sharpened one edge. Wish I still had that thing.