Cast steel: is liquid metal pored into a mold and then ground into shape. Many scissors that say “Japanese steel” are cast.
Forged steel: is made by heating and hammering rolled steel into shape. It is then ground into the final finish.
Under a microscope, the forged steel molecules are more densely packed together. This gives forged steel tensile strength (the ability to bend). Cast scissors will not bend, they will break into pieces. Forged scissors are able to be made sharper, cut smoother, and hold an edge longer than cast scissors. Forged scissors are usually made as two pieces. There is usually a faint weld line where the handle joins the blade. A softer steel handle is welded on to the harder forged blade. This is so the handles can be bent into shape. Another method is where the forged blade is screwed onto a handle as in the Yasaka scissors.
Hardness and tempering are as important as the type of steel. 410ss(Rockwell 38-44) often from Pakistan, is too soft. 420ss (Rockwell 48-52) is satisfactory, many German style scissors are made from it. 440ss (Rockwel 58-60) is a good scissor steel. A lot of Japanese style scissors are made from it. ATS314ss (Rockwell 60-62) is one of the newest steels.It is used on some expensive scissors. Damascus steel is ATS314 folded into layers.
Tempering is a final heating and cooling treatment that adds toughness to the steel. It must be done under strictly controlled conditions. Differences in tempering procedure effect the toughness and the feel of the steel, as you use the scissors.
Most stainless steels are a Molybdenum alloy. This alloy often contains small amounts of Cobalt. Cobalt is much easier to say, and takes up much less room on a scissor. So Cobalt is the word used. There are very few scissors made from true Cobalt. You can test for it, it will not attract a magnet. The only true Cobalt scissors I know of is Kikui Cobalt, and Joewell Cobalt and New Cobalt.