Carbon steel knives are easier to sharpen, and stay sharp longer. I like to degrease them and stick them in an onion for a couple of days. Rinse oil and use. The stain is called patina, and patina protects the blade from rust. Almost like bluing on a gun.

You are not alone, these days most people don't appreciate a nice patina, and don't want the extra maintenance.

I consider it beautiful. The older and darker the better.