Originally Posted by
Mike Blue
Without being able to talk to the smith who made the bar of steel, nothing is certain. Asking the person who made the steel would be the most direct and accurate means to answer your question.
We could subject the blade to destructive testing, say spectrographic analysis, and could probably discriminate between a very clean simple steel like tamahagane and a modern alloy, but some modern alloys are very clean and simple too.
It is possible that this blade is pattern welded regular steels. See above answers.
As Glen indicated, this type of steel has its own value. I can't imagine going to the trouble of using a fairly rare material and then not taking credit for it. Even pattern welded material should be more valuable than say a mono-steel. You have to recover the cost of the materials, the cost of the labor involved (as these are custom hand processes for the most part), some of the aesthetic involved in creating the work and the smith's reputation for working in an above-average material. But, the smith could have died and the blade wasn't stamped. Given the possibility that there are flaws in the blade, he may not have wanted it marked as his work and suffered some damage to his reputation. It could have been a master's student's work and not good enough for a signature. As I suggested though, the flaws I see are not fatal and while they would not be considered perfect work, you still have an acceptably adequate working tool to use too. Value laden objects are subject to too many variables.