This article is from the Fencing FAQ, by Morgan Burke with numerous contributions by others.
For foil and epee, there are a wide variety of grips
available that fall into two broad categories, traditional and
pistol. Sabre grips are all fundamentally of the same design.
Most grips are fashioned of aluminum or plastic; the latter,
while lighter, are also much more fragile and prone to cracking.
Some metal grips are insulated with a layer of enamel (colour
coded by size) or rubber paint. Such insulation will turn an
epee grip into valid target, but it is useful on foils to prevent
grounding. Many traditional grips are surfaced with leather,
rubber, or twine.