This is how I made my half leather, half wood sheath but I am sure there are many other ways.
The piece of bur you have selected for your sheath must first be cut in half (I used a hack-saw), then draw round the blade and carve out the wood on both halves to the thickness of your blade and mark out the shape for the finished sheath.
Glue the two pieces of wood back together and once dry carve the wood to the desired shape. Drill a small hole in the end of the sheath that reaches to where the blade will sit and this will allow any moisture out.
Using newspaper pack out any narrow parts where leather shrinkage would prevent the knife being withdrawn. Then cover the handle with foil which will prevent leather dye staining the handle and make it easier to withdraw the knife after the leather has shrunk and dried.
Soak the leather until it is soft and pliable and if you want to make any pattern in the leather now is a good time to do it. Place the knife in the sheath and then wrap the leather around and secure the ends with bulldog clips.
I used “saddle stitch” to sew the sheath together, using an awl to make holes in the leather. Once sewn together mould the leather using the rounded nail and work the leather into the two grooves. The leather is then left to dry and of course shrink and then any excess can be cut off.