I think this applies to the higher quality less mass produced Japanese knives but a refinement that one should be aware of none the less.
The knife be it a single sided knife like a Yangi or a Deba or a Kamagata Usaba makes like Korin are likly to include this feature it is often done only on one side even if the knife is a normal double bevel and is probable the product of three sweeps on the finishing stone .The bevel will be about a hairs width.
A Deba is used to cut up big fish or poultry the front two thirds of the knife is used for filleting when it is necessary to take of the head the knife is push cut through the gaps in the bone . Most Debas are one sided so the bevel although high is more fragile due to its chisel like geometry.
So as to strengthen the back third of the blade a double bevel is put on it the Deba is not used as a cleaver the arms are held straight , the heel of the knife is placed on the area to part and then the full weight of the upper body is used to push cut through the vertebrae .
Excuse the poor quality pictures the last picture just about shows the section that is double beveled the middle picture shows roughly where the double bevel area begins which is roughly between the M and the blue logo and the middle picture shows the right hand side of the knife’
Incidentally i picked this up for just under half price from CKTG since there is a very minor handle issue that you would not notice unless you were looking for it.
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