This article is from the Fencing FAQ, by Morgan Burke with numerous contributions by others.
FIE-certified blades have the FIE logo stamped at the base of the
blade, along with the code letters for the forge that produced
the blade (caveat emptor: some disreputable forges have been
known to falsify these marks). They are mandatory at official
FIE and other high-level competitions.
Maraging steel foil blades have a reputation for lasting
considerably longer than regular steel blades, and are supposed
to break more cleanly. They are made of a special alloy steel
(incorporating iron, nickel, and titanium) that is only 5% as
likely to develop the microcracks that lead to eventual breakage.
Many fencers find them a superior value - although they cost
twice as much, they last much more than twice as long. As they
vary in character in the same way as regular blades, similar
caution should be exercised when purchasing them.
Maraging epee blades are also available, although there are
alternative steels that have also received FIE certification.
Leon Paul produces a non-maraging FIE epee blade worth
mentioning; it is stamped from a sheet of steel, rather than
forged whole. These blades are lightweight and flexible; some
older ones passed the wire through a hole to the underside of the
FIE 2000 sabre blades are stiffer than older sabre blades, which
is intended to reduce the incidence of whip-over touches.