While many believe that folding makes the blades "sharper", it is not true. It is as Heir of Black Falcon said to remove impurities in "bad" steel and to make it even. If you would use industrial steel of today, that would be unnecessary. However. It was also used for decoration. If you have two slightly different steels, and fold them together over and over again, it will create a pattern when you put the blade in acid id the two metals have different ways of reacting with it (color change). The result is sometimes referred to as Damascus steel. Some Wiking swords were made that way to make them look beautiful.
This is a nice forum regarding forging.
http://www.iforgeiron.com/forum/
However. almost
every young man who wants to learn how to forge, will quickly try to make a sword blade (one of the hardest skills in forging) and find it too difficult (which it is) and quit.
Sword were made by several persons. Usually they had pre-shaped sword like pieces of steel, that the blademasters made into blades, the someone else polished them (who was an expert at that) and others made the handle and others the scabbards. It was a task that many experts were involved in.
I started forging because i love swords. Of course i tried to make blade almost the first time (with regular iron, not hardenable steel, which is good for practicing, since steel is more expencive). They do look very orkish,
and ugly.
But i went on a knife forging course and made a very nice knife blade. the instructor hade made swords as well, and said it was basically the same technique, but in a larger scale.
For making knifes, we took a suitable piece of steel, that was wide and thick and long enough to start with. Shaped it into a knife shape, staring to draw out the tang where the handle will be. After the forgin, i had the shape of a knife, but was blunt. then we filed the edges so that it had the exact shape it should have, including the edge. Then we hardened it. Heated it up to a high temperature in the forge and cooled it rapidly in oil. this way the grain structure remains as it is in the heated state, and it makes the blade very hard but brittle. Then you need to reverse this process little to make it slightly more durable. This is called annealing. you heat it up to around 300 degrees in an oven and have it there for a while, then let it cool slowly. After that, it was polished on a grinding stone. and the edge became very sharp.
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