The wrap under the cord can be anything that will hold up to use. If the knife/sword is decorative, it can be wrapped in almost anything. Here are a list of choices:
Textured leather - Kudu, ostrich, elephant, buffalo,etc.
Exotic leather - Snake, Lizard, alligator, frog,walrus, seal,etc.
Rawhide,deerskin,etc.
Material - Silk, velvet,felt, canvas,etc.
Cord - anything from thread to paracord to leather lacing.Wind in a continuous spiral and seal with lacquer or resin.
Wood - no wrap needed if the handle is on a decorative show piece. Make the sheath of matching wood. - Snakewood, bocote, bubinga, etc.
You could even do the handle in lacquer, or cover it in gold leaf.
How about applying a base of black lacquer and building up clear layers with tiny flowers (cherry blossoms) in the clear coat. Wrap with a white or pink ito.Make the saya to match.
I think you should get the picture by now - The possibilities are endless.
Stacy