First question is: what is the intended use of the knife? User or show piece/collection piece? That drives things into separate directions.
For users, I have a set of design features I look for, varies depending on intended use. A lot of this is ergonomics, which speaks to useability and safety in use. Some of it is a preference for design features or parameters, other is a rejection of some features that I've found to be a nuisance (upper guards in some applications, sawback teeth, trailing point blade profile, etc.)
Then I examine fit and finish, action and lockup on a folder, etc. Particularly important on a folder, a much more complicated gizmo to design and fabricate well than is a fixed blade.
Then I want to get a feel for whether the maker takes the craft seriously with respect to the knife's intended use (if it is going to be a user). This gives me a clue on both durability of fabrication, and quality of heat treat, and design's fitness for purpose. Maker reputation fits in here.
Of course I have preferences on handle materials and such.
I want to understand the cost vs. quality vs. likelihood I could get most of my money out of it should I choose to sell it.
I'm another who doesn't choose to spend money chasing historical significance. I can relate to why others might.
Blade steel: I might not care on a show piece, where I wanted a mirror polished blade (440C or RWL-34, not sure I'd care). Damascus is obviously for looks... I don't ascribe any performance benefits to damascus. For a user, blade steel is important to me personally, along with specs for hardness and understanding about ability of person doing heat treat.
For a field carry knife, sheath matters. For a pocket carry, a small sheath helps in carrying a folder in dress clothes, and a good clip for a user or routine daily carry in jeans.
Example: I've often spotted a neat looking design that looked like it would be a comfortable, practical using knife, and thought "don't know much about this guy, I'll save pic and think about having Joe Blow make something like it for me out of CPM 3V at Rc61 and an inch longer, but in ironwood handle and minus that feature (recurve, top guard, etc)..."