I've seen a lot of references to this knife because I was interested in it, too. From what I have been able to gather, the knife is WAY, WAY too thick for its size, so as a result it cuts and stabs poorly. Considering that is the purpose of the knife, it doesn't make a whole lot of sense.
I haven't seen anything about the sheath itself, however, although in my experience sheaths are easily replaceable and you can get a Kydex sheath custom made that suits your needs for around $30.
From my own point of view, I think the research and reasoning behind the knife are sort of negated by what it is. I mean, the knife is supposed to look like a kitchen knife so that it is less conspicuous, but if you get caught with a kitchen knife in concealed carry in a Kydex sheath, no cop in his right mind will say "Oh, you must be on your way to the kitchen!"
I think the way the knife actually looks totally negates this logic. If you're going to carry a fixed blade for a defense knife, you may as well carry one that works right because you're screwed if you get caught with any of them.
------------------
My Custom Kydex Sheath page:
http://www.geocities.com/CollegePark/Lab/1298/frames.html
Palmer College of Chiropractic
On Two Wheels
agocs_s@dd.palmer.edu
Madpoet (Mel Sorg, Jr.) Tribute page:
http://www.geocities.com/CollegePark/Lab/1298/madpoet/main.html