because it has advantage and disadvantage
The blade on a RIFLE is called a bayonet.
A two-tipped spear is called a double-headed spear or a double-bladed spear. It is designed with a blade at both ends for increased versatility and effectiveness in combat.
There are three types of fencing swords each with different rules : Foil, Eppe and Sabre. The blade of a foil is called a "Foil blade"The blade of an eppe is called an "Eppe Blade"Etc
The edge of the blade should be called as edge of the blade. But in practice the cutting edge is probably called as margin of the blade. The expert in English language should explain better.
It is called the rotor.
The ridge on the dorsal surface of the shoulder blade is called the spine.
A double edged sword is a sword, with a blade that can cut with both edges.
The blade at the end of a stick is called a "Bayonet".
double,poison and pistol
Lancet
Doppelklinge = double blade
The name of the blade that stabs Frodo is called a Morgul-blade