
Sorry if the image is too big...
But anyway, I was going to say his pants are black, but after double checking with a few images, the sound uniform has more of a dark-gray color (mostly Orochimaru).
Though I've seen many with black pants for Orochimaru...
My suggestion? If you want it to stick apart from the sash/skirt/thing overtop, go with a lighter shade of black (or gray).
As for the katana, make a wooden one (since live steel isn't allowed, yada, yada, yada...). You can also paint it to look real (much like people do with say...Cloud's Buster Sword from
Final Fantasy VII).
I hope that helps.