"Maraging" steel is a specific kind of high chromium steel, approximately 36% chromium. Also used in golf clubs. Is used this way to due purportedly high resiliency (and in foils) less breakage.
To my knowledge, all commercially produced foils in the world are drop forged. I have never heard of one being hand forged - but obviously, it was done this way at one time.
A new book has just been published "By the Sword" - Richard Cohen. I haven't read it, but is supposed to be comprehensive and readable. Don't know if there is any steel info there.