I also enjoyed the book, and reiterate the cautions that this is a
popular treatment rather than a
rigorous treatment.
On steel: most smiths knew how to make steel, and although nothing like the amounts we know today from the Bessemer (and other) industrial production processes was known, there were relatively many steel swords around (not just case-hardened iron, although that too was not unknown). A smith could make a batch of steel sufficient to make fifteen or twenty swords in a couple days' work spread over a few weeks (there were parts of the process that had long lead time, but little production effort- mostly a matter of waiting for the process to happen, rather than working continuously on it), and could make a steel sword from the batch of steel in a few days, and one should not underestimate the number of smiths around. It is, after all, one of the most common names in the English language, and there is a reason.
The finest swords of pre-industrial times were made in three places, using three different methods. The overall idea was the same, but the execution was as different as can well be imagined.
The overall idea is to layer high-carbon, very hard but very brittle steel between low-carbon, softer, but more flexible mild steel or writhen iron. There must be many thousands of layers per inch, alternating the harder high-carbon steel with the more flexible writhen iron. Over-layering, however, eventually will result merely in homogenization of the steel rather than the desired layering.
The Japanese
katana, or "Samurai sword," actually only one of two blades carried by the Samurai but the one that everyone in most Western cultures associates with them, was made by case-hardening a steel bar, beating it flat, folding it, beating it flat, and repeating this process until the high-carbon layer on the outside (created by the case-hardening process) had been layered many thousands of times with the low-carbon writhen iron in the middle. Most swords were folded twelve times or less, and twenty is theoretically sufficient to homogenize the steel to a level of less than molecular width.
The sword-makers of Toledo learned some of their art from the Arabs, and the rest from experience; their process for layering involved the production of two case-hardened bars, which were welded together and then twisted to produce a swirled rather than a flat pattern as in the katana.
The sword-makers of Damascus used a process unknown today; what is known from analysis of the isotope content is that they began with wootz steel, but what processing they used to produce the final product is still debated today; if it was pattern-welding, it utilized techniques that are no longer remembered. One group has it that ten or more cyclings of temperature to very precise levels both up and down were required at a certain point in the process, and has demonstrated their technique and produced swords very like those of the smiths of Damascus.
In any case, the three tests of a true steel sword are these:
The steel can be sharpened until it will cut silk from the air; that is, if a kerchief of specified size is thrown up into the air, the sword can cut it as it falls unsupported save by the air itself.
It will cut a lesser blade. By this it is not meant that it can cleave it, although that is a possible result if the opposing blade is of a relatively soft metal; rather, what is meant is that the steel sword can be used to shave the hardest part of a blade made of something of lesser quality than steel, normally the edge.
Its hilts can be bent to meet its tip, and when it is released it will return to its original form.
These three tests can all be passed by any high-quality (read: old) katana, Toledo sword (but be careful that it is truly made by the Toledo process- there are many that are not, yet come from Toledo, which were made by methods other than pattern welding, or from inferior materials, for common soldiers, footmen, and so forth), or Damascus sword. I would, however, caution that even if the sword does not break, one could easily lose life or limb in conducting the third test!
In modern times, detailed understanding of the crystalline structure of steel and the use of additives of various sorts to modify it in various ways allow us to create homogenous swords that are nevertheless superior in quality to anything that could have been made by pre-industrial smiths; however, we no longer require swords!