The two main processes used in shear manufacturing are cast and forged. In the process of making a cast shear, liquid metal is poured into a mold and then allowed to harden.
Forged shears are made from molten steel that's poured into a die and then hammered to ensure that the scissor is perfectly formed, both inside and out. The handles and blades are made of different grades of steel, one being best for the blade and the other having optimum characteristics for the handle.
However, the "forged" tag alone doesn't guarantee that you are buying a better shear. Both can be made poorly and end up in your drawer, never to be seen again. The solution? Only deal with reputable scissor companies that are established, committed, and deeply involved in the art of making shears.