Unfortunately, the pockets on the Bussee sheaths are stitched into the sheaths. On the bright side, I do like the functionality of these pockects. You can't really tell from the pictures, but the pocket has bellows design to it where (though only as wide as the sheath) the pocket has good depth to it. In my eyes, there is actually room for another pocket on the Battle Mistress sheath.
In the pocket for my Battle Mistress sheath, I keep a Leatherman Wave, a Lansky two-sided diamond hone, a blast match, and a bottle of Potable Aqua. It's a snug fit, but the I can keep it snug with the top strap that closes over the velco patch. Wrapped around the sheath, I also keep a nice length of paracord.
The basic rule is to be able to make fire and cut things. If no other equipment is available, this little setup gives me the absolute essentials to make it on my own for a while.
Hope this helps!