I think materials are the first thing that puts a knife in the "high line" category. Very few of us (forumites) have access to a knife shop stocking a range of $100+ blades (yes, I'm making an assumption). So premium materials that we've heard about somewhere - S30V, carbon fiber, titanium, etc. etc. etc. - are an indicator of a quality blade that we can't handle before buying. Cheaply constructed knives tend not to come with these materials. Lots of makers with second-rate reputations have entered the "high line" market by putting out a few blades with preminum materials and/or collaborating with a well-known maker to put his name on a few models. (I don't put Spyderco in this category - the collaborations came after the company reputation was well established).
So materials open the possibility of a "high line" product. HOWEVER, quality becomes the deciding factor. If I'm going to pay big bucks for a blade, the fit and finish better be darn near perfect. Example - I'm a big fan of HI khukuris. Every so often, someone complains on the forum about a little dimple or a blade that's less than straight. In my mind, things like that come with a blade that's hand forged without modern technology, for about a hundred bucks. They perform great, but they're not High End. However, if I get the same thing from Chris Reeve or Jerry Busse, it's headed back to the factory. People have complained on this forum about a Spydie that wiggles a fraction of a millimeter. Again, on a $50 Delica, that's OK with me. But on a $300 Sebenza, I pay for someone to spend a day tweaking it to perfection, if needed. Most BladeForum people who are really into high end knives seem to pay attention to how a folder is put together and have really tight personal tolerances. They don't just care how it looks. Regardless of materials, if the rubber doesn't meet the road perfectly, your reputation is going to suffer.