Hi Friends,
The question was, "What makes a knife pleasing to the eye?" Yes indeed, balance of parts and proportion, as well as color and texture, flow of line and curve, quality of fit and finish (or craftsmanship) are all important visually.
Some answers have reached out to other senses. For instance, the "sense" of functionality and concept, if you will. This is where the shape, size, geometry and composition of the blade, handle and hardware specifically come into play. Durability does too I suppose. Then there is originality and familiarity. Is the design a good old tried and true friend? Is it an interpretation of such? Is it new and refreshing and begging to be put to the test? I guess safety is also an issue in this realm. It certainly is a part of functionality anyway. Whether we think about it consciously or not, I'm sure it comes into play in what we "sense" as a good knife.
Of course, the sense of touch is very important too. How it fits and feels in the hand is, perhaps, even more important than how it looks to the eye. It's interesting to note, that that which feels good in the hand usually looks good to the eye anyway. I suppose, how it feels and fits also applies to the belt, pocket, pack or bag too.
I bet sound and smell come into play too. I find myself semi-consciously listening for the sounds of a folder closing and opening. I listen, too, to the sounds of a sheath knife nesting home and being drawn. I remember loving the smell of cleaning hunting guns and catch myself sometimes tripping down memory lane when I get a bit of a whiff of leather and oil or wax when handling knives.
Oh well, here's my two cents anyway. Thanks for stimulating some cogitation.
All the best, Phil