Good question, Roland
I may used the term "impurities" incorrectly as your blade shows some linear layering - a form of deliberate mechanical manipulation of different steels. Please see
THIS POST for better example of what I meant by "impurities", i.e. pattern that is not formed intentionally. As you know, true wootz is a result of different impurities that were part of the ore, not added/manipulated to form the (mechanical) pattern. With examples above, the pattern is formed due to different steels used in the mix.
Question to metallurgists: does the fact that "Each side has its own pattern" indicate accidental/random pattern formation, any particular technique, etc?