OK, I am truly schizophrenic about this. On the one hand I love my collection of knives. I have a buck that my Grandad gave my dad and then he gave it to me on his deathbed. Love the feel of this pocket knife with its rosewood handle -- I carry it most days. I have a pearwood handled Opinal, which is a 2.5oz monster, that I carry often when backpacking. I enjoy the wood handled feel and opening the razor sharp carbon steel drop point blade that is discolored from use and cleaning fish or whittling. You know whittling is a forgotten art that relaxs the mind, occupies the hands and creates something of beauty (as well as making a great toothpick for after dinner!)
Most of the time I carry either my Opinal or I carry a delrin handled gutting knife with a 2" blade weighing 1.5oz when I backpack. I feel naked without this piece of survival gear. But as one poster noted, a knife is not really "an essential" now is it?
(By the way, maybe it would be a good discussion here in the forums to really take a hard look at the 10 Essentials.)
So the other side of me, the lightweight backpacker side, often feels that I am betraying the cause of lightness by carrying a knife like the ones I own. I wonder how many of us suffer from this dicotomy. I know I need a pair of cuticle clippers because of the awful hangnails I develop on the trail. These I have use often and are a light .5oz. I know I need something to cut tape, bandages and other 1st aid stuff. So a sissors may be useful although a very sharp knife works, too.
Seems the best answer may be the Swiss Army esquire or classic at .6oz to .7oz.
But what happens when your arm is caught in between a fallen boulder and an rock wall miles away from anyone else and you have no way of escaping unless you are willing to perform an amputation -- Huh? What happens then?