I own one of the older "Large" FF. It came in a tight and snug kydex sheath that has the profile of a check book. No chance of it dropping out of the sheath, as the kydex has a positive lock on the finger guard. But because of the way it is constructed, a quick tug on the part of the handle that protrudes, puts the blade nicely in the hand. I guess that's pretty similar to most well constructed kydex sheaths.
The FF comes across as very "plasticky". The knife is one solid piece of composite that has been profiled in to a slightly drop-point blade. The heft and feel is about the same as my Spyderco Delica. Which is quite amazing for a knife that has an overall length of 8". It just weighs a couple of ounces.
I followed the sharpening instructions adviced by Kevin (use very fine diamonds or sandpaper of about 12,000 grit) and managed to get what I felt was a nice sharp edge on it. The edge grinds down quite easily and quickly, so you have to be careful not over do it. (Like sanding down acrylic plastic) However, when I gave it the paper slicing test, it didn't perform very well. The cut edges of the paper were similar to the sort of edge you get when you open an envelope with a letter opener, ie a bit rough.
In an idle moment, I also tested the edge by pushing it against one of those plastic knives from MacDonalds, edge to edge. To my surprise, the edge on the FF gave way till just past the primary bevel. The MacDonalds knife had an indent that was just slightly deeper. Fortunately it wasn't too difficult to resharpen the edge.
Next, I tried stabbing a piece of wood. I think this is where the blade really shines. The knife was of sufficient thickness to remain totally stiff. It did not bend or flex. However, it penetrated only about 1cm in to the wood (taken from a wooden pallet) and the tip became slightly blunt. But it penetrated to almost the same depth on subsequent stabs without becoming more blunt and without requiring more force.
In my opinion, the FF is really a last ditch weapon to be used for stabbing attacks rather than slicing. It is NOT to be used as a general utility blade, or you'll soon grind it down to a stick.
If you are looking for an undetectable blade, you might also want to look in to the titanium stuff. I have no experience with those blades yet. But to point you in the right direction, here are some names.
Boker Orion (Ti)
Boker Infinity (Ceramic)
Mission Knives (Ti, but very expensive)
Newt Livesay Titanium Tiger (Ti neck knife)
Hope all this helps.
BTW, I also own a MD Mirage EOD. For the performance of the blade, I think it's pretty good and the edge is far more durable than the FF (of course), but just bordering on the point of not being worth all the money.