A useful hunting knife IMHO has a sturdy blade about four inches long and a substantial handle that gives a good grip under less than optimum conditions, such as when it's cold and the grip is slippery with blood, fat, etc. I like a flat grind for ease of sharpening. A drop point is useful because it allows you to easily open the paunch without cutting the intestines. However, a clip or upswept tip can also do the job but require more care when doing the opening chore. The steel should be good quality and hold an edge for a substantial time. I prefer carbon steel (1095, Carbon V, 52100, or Roselli's excellent high carbon steel) but there are a lot of good semi-stainless (D-2) and stainless steels out there (AUS-8, ATS-34, VG-10). A finger guard is optional. Kraton grips are totally functional when it comes to giving good grip but some people don't like them. Roughed-up micarta grips are recommended by some professional hunters (Ross Seifreid), wood is great (I love the Arctic birch of my Roselli), stag works well, stacked leather does the job. I think Cold Steel's Master Hunter is outstanding, along with their Elk Skinner and American Hunter designs, all in Carbon V. My Roselli erapukko, Marble's Fieldcraft and Campcraft are also great hunting knives. Buck makes excellent hunting knives, too. One under-rated knife is Grohmann's Russell Belt Knife (made in Canada, yea!). I've used a Cold Steel SRK when skinning a moose and it worked great. Really, the user is the key. A useful hunting knife should also have a good sheath, but that's a whole other topic.