Not much to add to Mr Kavanough's typically thorough description, but I would just say that a sheepsfoot often does have a point of sorts. If you were to take a butter knife and divied it in two end to end then you would have two knives each with a sheepsfoot shape to them. The cutting edge is generally flat (sometimes serrated) and the front, where the point of most knives is, curves neatly down to it. Consequently you can stab yourself with a sheepsfoot, but it's nowhere near as penetrating as a clip- or spearpoint blade. The British Army penknife has a sheepsfoot blade.
You will occasionally see knives with a tanto point. These are styled on the Japanese tanto (of course!) and usually feature a slightly upwards-curving blade with a straight, but not vertical, front edge, usually sharpened. Supposedly the design comes from making a dagger out of a broken sword, but I've heard other theories so who knows? Blade fans love to debate such things. If you want to provoke an argument just get three of them in a room and ask them at what point a knife is considered a sword.
Anyway, in practical terms I would suggest that any knife not being bought for a specialist use should have a fairly robust, which usually means reasonably short, point to it. Spearpoint, a la Swiss Army Knives, is fine, but anything with a "spindly" look to it has to be suspect in terms of hard use. I have a very nice little pocket knife bought years ago in America which gets much use, but the blade runs to a narrow clip point, and I would never use it for the slightest leverage.