The critical point that I would like to emphasize from this article is that 440C steel is not an alloy designed for sword blades however well it may hold an edge. As a mass produced and readily available material it is a less expensive choice than some alternatives designed for sword construction while having many benefits over lesser alloys. Many manufacturers use this alloy for their swords, so this article just provides a simple perspective to some of the possibilities. The article is published in unedited form until I'm able to get permission from Mr. Lipinski to extract the pieces of immediate interest to swordsmen. In order to understand tool quality, one should have some understanding of steel.
Steel is basically an alloy of iron and carbon.
More specifically, it is iron that has a carbon content of 1.7 percent or less. The addition of carbon makes the metal harder, but also more brittle, less malleable and less able to withstand stress and shock. Manufacturers recognize that different tools are subjected to different amounts of stress and shock, so they match steel with a suitable carbon content for each tool. Too-quality steel must have at least 0.6 percent carbon content. This relatively small amount of carbon insures that the steel can be heat treated.