If you want to be really original and if you're good at handcrafts maybe go as a samurai. You don't have to exactly look like one, but you could go to the hardware store and buy sheet metal for your shoulder pads and decorate your costume with brass chains, or something like that.
That would be a lot of work, but if you're into crafting things you might want to give it a try.

Heh. Speaking of armor.