This is only an idea so far. Nothing's set in stone.

Just like in Kyo's Wasteland gear reference ( http://www.furaffinity.net/view/9627124/ ), the silk has faded, so it's no longer shiny, the laquer on the scabbard has lost its sheen and is starting to crack and flake, showing the wood, and the metal fittings, the tsuba especially, has rust, scratches, and dents (add however you see fit).

What I added, though, was that the shakudo parts are patina'd to a very dark blue-violet, almost black. The gold still remains gold, adding a nice contrast. Also, the samegawa (rayskin) on the handle has yellowed with age. The blade, however, is still like new.

Shin-Okami/image © me
Wasteland concept ©  Metal