A lot of times the sheaths get lost in translation. I have several swords with frogs that hold the sword up and down so vertically that you have to draw them at a weird angle. It doesn't make them poorly made, but I think a lot of times they sort of toss a loop on it and call it good. If I don't make a whole new sheath, I usually at least make a new frog for the scabbard.
I can see this knife benefitting from a custom back draw sheath at about 5 o'clock that ends in a comfortable reverse grip. I generally ascribe to the "get as much blade out in front of you to keep the bad guy further away" grip as I am a painful novice when it comes to knife fighting, but this nasty little claw screams to be used in a quick and decisive and gut-spilling manner.
It doesn't look like a knife for "locking steel". It looks like an equalizer for times when an assailant thinks he's going to give you a really bad day and doesn't realize until he has you pinned on the ground that things are looking much worse for him as he's been unzipped kidney to kidney. I could see this being brutal when fight or flight dumps an elephant's worth of adrenaline into your system, your pupils grow wide and feral, and your body assumes a naturally reflexive crouch. Call it a tooth or call it a claw, it sure looks like it would do the trick.
Doggoneit, I talked myself into one now