I've just watched the Berserk 1997 series. During the entire series, Guts has both arms,
until the end where he cuts his left arm in order to try to rescue Casca.
At the beginning of the series, before his story starts to be told, he has an arm that seems to be made of iron or something. It appears to have some firing capabilities, which in this anime series is never explained, or how he got it. What does Guts have in his left arm exactly and when did he get it?
This arm is never explained in the 1997 version of the anime. The arm is a prosthetic arm with a few abilities, most notably the cannon. It was made by Rickert after the events of the Eclipse. I don't think it is ever mentioned what the arm is made of but I believe it was made using various materials. Guts can not move his fingers of the arm, and the hand has a magnet to hold his sword. He can however, move his fingers when he goes into his berserker state, but that is a result of the Berserker armor, not himself or the arms functionality.
I haven't seen the new Berserk anime yet, only the golden age movies, so I don't know if they elaborate on the arm in the new anime. The golden age movies ends just after the Eclipse, before Guts gets the new arm. I would assume they would elaborate on this in the new anime at some point, in a flashback or something.
