I cant remember a cool anime show that i once saw, can somebody help me out.?

Ok, one evening a couple months ago, i was watching cartoon network. it was kinda late (don't remember the exact time) and this cool anime show came on. i could tell it was a Japaneses made show. its about this guy who looks about 20, and he has red hair. when he gets into a fight, he gets a golden armor around his arm. in this episode, he was using "Blitz's" i think for attacks. he had three of em till he lost his armor. He was fighting this BIG monster type guy controlled by another human. o and he seems to have duel personalities. If you know the name of this show, i would really appreciate it. Also, where can i download most of the season from?