Another option
On a different note, I’m from the option if I hate it I change it.
If you hate the shiny finish you can always get a matte lacquer and refinish your saya.
If it is scratched this would be a good time to cover them with a coat of black, then use a matte or satin clear coat.
Or use a textured black then cover it with a matte or satin clear coat.
Before you start:
Wash the saya with dish soap and water (remove the oils) before doing any refinishing also, you may want to roughen up the existing base with some steel wool (take care not to breach the color coat or you will have to recoat with black) then wipe all residue before refinishing.
Just an additional option.
All My Best,
Todd Wayman
"…since karate is a martial art, you must practice with the utmost seriousness from the very beginning."
- G. Funakoshi, Karate-Do Nyumon, 1943