I am going to take a shot at explaining how I think it may be done!! The only way I have of showing what I am speaking of is some pictures of some rough drawings. So don't laugh too hard!
Lets say you have your sheath, the outside is the finish side and any work you want, at this point would already be done! Whether that would be carving or stamping and belt loop, as well would all ready be attached. You are going to do a liner for the inside of your sheath from a lighter weight of leather.
This picture would be the outside of the finished sheath with design on face and belt loop sewn to back. All you would have left to do if you were not going to use a liner is fold it over and stitch the edge!
Lay your sheath down finish side out and lay the inner liner for the sheath on top of that rough side out, (make inner liner larger all the way around). This pic is that inner liner, laying on top of the finish side of the sheath. The inner liner at this point is rough side out! The line at the bottom would be where the actual point of the sheath is laying below it. That line is just for reference it would not really be there!! Be sure to make the inner liner slightly larger all the way around. The top will need about an extra 1/2" to 3/4"!
Fold about a 1/2 - 3/4" of the inner sheath rough side out over the top of the finish sheath and stitch the two together. Now fold what will become the inner liner over the top of the sheath. This will create your finish side out welt at the top of the sheath.
You now have a outer finished sheath and the rest of the inner liner is glued to the backside of the finished sheath. This makes the inner liner finish side, towards the blade and when the glue is dry trim the inner liner to match the outer sheath fold the whole thing at the center line and stitch the edge of the sheath!!
I hope this all makes sense, cause this is the only way I could figure to explain what I was talking about! :what!: :biggrin:
Sorry the pics are out of focus when they enlarge it makes them our of focus!! Also not sure why that second pic is attached thumbnail I thought I deleted it after I posted it right side up, instead of the on the side pic. Oh well I hope this helps!