I have a question now. If you etch a damascus steel blade then put it trough hot bluing will the etching still remain visible at the vary least when looking closely?

there are numerous things you may be aiming for when you etch , contrast depth of etch and an element of "matting" from acidic action. I dont hot blue stuff but do do very similar stuff with coffee and tea (hot) and prefer the results I get after a deep etch. etch first in vinegar to get depth , then ferric cor some kind of conteast and a little more depth and the the boiling tea/coffee for deep darkening a light pass over with 6000 grit to clean up the high spots.

I sometimes use a "surgical black" novaculite  stone to go over a blade after etching and  colouring to bring up the Ni layers brighter.  I use it with WD-40.