Thanks for posting the pictures.

I currently carry my keys in a case like that, and it has a couple of things in it- a "hot spark" flint and a Photon 3- although I carry my P-38 in my wallet. I use the big ring at the "bottom" to carry the remote for the car alarm, which in itself makes the whole thing too bulky.

It's a handy device, but not with me as constantly as my wallet and other pocket contents, and a knife it will hold is going to be pretty easily concealable anyway.