Blue eyes are much more sensitive to light than brown. For night vision, it's a huge advantage. So in the far north where it's dark for much of the year and even in the summer time never gets much intense direct light, blue eyes are more adapted to that. Everywhere else in the world, it gets very bright for much of the year. The more sensitive blue eyes get overwhelmed by all the direct sunlight, so they either need to wear sunglasses or the eyes could be damaged. Brown eyes block more light from getting in so they don't get hurt from too much light. Most Europeans used to live in thick forest with a lot of shade, light was scarce so blue eyes were the most common. Now most of that forest is gone, we live out in the open now right under the sun. So brown eyes are more common. This is just simple adaptation to better match our new environments.
Same thing with blonde hair. It doesn't block much light so the light is allowed onto the skin where the body uses it to make vitamin D. This is why most children usually have blonde hair even if it turns darker when they get older, the growing child needs a lot of vitamin D. Blonde hair is made for places where there is little light, whatever small bit they get they need to be able to absorb. But when the sun is too bright, now there's all kinds of problems like sunburn and other harm. Blonde hair doesn't block any sunlight. So the hair has melanin in it to block the light to get some shade protection. Same as in skin that isn't very pale. Same as in brown eyes.
If you are Skanðinavian, do your work for blue eyes and blonde hair because you surely need it there. (By the way Skanði is another name of Shiva and Satan. Skanði Navia is Skanði's islands or Skanði's place by the sea.) If you are basically anywhere else in the world, the brown hair and eyes is much more of a benefit to you than you considered. There are many different genes that control color of hair and eyes. And the light colors are usually recessive, so if you're white you almost certainly do have the DNA in you for blue eyes and blonde hair, you just might not see it. But you mix together for example 4 parts clear liquid and 1 part dark brown and all of it looks brown. The DNA is in you already that you want, you could use Satanama to make that specific DNA more active and the brown DNA less active, but it seems like a big risk and a huge amount of work for basically nothing. If this is about trying to be closer to having the DNA of the gods, you already do have it in you, you just also have a shield to protect from excess bright light. For many changes like this that people want to make, when they look at the implications and interactions between every little piece, it really wouldn't be an improvement.