You know what the blotching is right?
It's light surface tarnishing called a 'patina', it's caused by a chemical reaction with the carbon steel blade and things like blood, acids etc found in fresh wood and wet foods/meats.
If you leave the knife for years it will go very dark and looks kinda like this..
It's normal for non stainless metals to form this patina, but if you don't like it you can easily remove it. Get some autosol polishing paste (found in all the diy shops) and add some to a strop and it will remove any patina and keep your knife sharper than ever!
A strop easily be made from a block of wood and leather, card or whatever stapled to it!
Hope this helps bro