How does one keep a knife in pristine condition

[Andy]

For periods between uses it's normally recomended to keep the knife out of the sheath, you can help protect the blade by using tuff cloth as well

 

[Wayland]

My knife has got heavily stained from using it to cut up a sausage, would the vinegar method change the blade to a uniform colour, so hiding the stain?

The vinegar will oxidize the blade towards the sort of colour you see on old steel kitchen knives, such patinas are often not quite uniform but add lovely character to a blade.

I suspect it may well tarnish the rest of your blade to match but there is no way to be certain.

As a tip try to remove any grease or oil from the blade before adding the vinegar or it may mask the steel from the effect. I clean it first with some lighter fluid if I want to be fussy.

If you want really uniform then buy stainless and keep it in a drawer...