Deba is knife for filleting a fish (taking the bones and bowels away) .
You can also cut meat and chicken including thin bones without losing edge.
Carbon Steel knife cuts better than stainless steel, but it is easy to rust.
Good maintenance is required after using.
Only one side must sharpen (sharpen the left photo)
To avoid oxidation: clean with hot water and dry quickly after using. and protect with a little oil.
It is an idea to save carbon steel knife. Oil of the book prevents oxidation.