If you still only have the Oathblade and are wanting to dual wield, on the PC version when you follow Delphine into her Riverwood hideout there is an unenchanted Blade sword hanging on one of the weapon stands. I'm guessing XBOX stuff is similar so maybe you can check in there too.
Armor is another thing though...not sure if you are going for an armored look, half-armored look or the full kimono look. I used to play Samurai Shodown 1 and 2, and i liked the way Yagyu Jubei dressed. Thats kinda what i picture when i hear about your wandering ronin. Its gonna be hard though since there isnt a separate leg or chest armor. Probably hide bracers, sandals (dont know where you can find it on Xbox though). None of the robes i've seen have the double flap in the front, just the single flap. For regular clothes there is the "Fine Clothes, which has a quilted looking outer garment with a double flap. For armor i was looking for a chestpiece that looks like the chestpiece on common samurai armor, but i couldnt find anything. The Dawnguard armor looks like some of the "Christianized" samurai armor i've seen. And because of Skyrim armor being combined chest+leg some of the chestpieces that could pass for a samurai chestpiece are ruined because they have the crappy leg flaps (steel plated armor for example).