Although Urushi doesn't need maintenance due to its superb durability, following maintenance will make a difference in the long run.
Do not expose the ebonite to direct sunlight for prolonged time.
This will cause the surface of urushi to become clearer.
Also prolonged exposure to artificial lighting also cause the same effect.
Although it will take much longer time, It will happen eventually.
Ironically for tamenuri products, this effect may be desired by users,
as clearer surface brings out underlying color more.
If you want to repolish, rub the ebonite with "swirl removing compound" + 100% clean cotton.
Make sure cotton is free of dirt, otherwise scratches will occur.
Do Not use #3000 compound, this will cause scratches that's visible under strong light.
You may use small amount of baby oil on urushi to bring out shine.
Also put small amount of baby oil to threads if you want to.
To bring out more shine and protect the surface a bit, use automotive carnauba wax.
apply the wax with your fingers, wait 10 minutes, gently wipe with clean cotton cloth.