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?