I have been carrying a Leatherman Mica in my first aid kit because it is light and has a great pair of scissors. For many years backpacking I carried the simple little classic Swiss army knife (now called cadet, I think). A small pocket knife is all you will probably ever need. Don't get in the trap of taking something heavy "just in case". If weight were not a consideration I would carry the Rambo III Stallone Signature Edition Knife. But weight is a consideration, and it would be foolish to carry such a tool/weapon. Same for a pistol. If it didn't weigh anything I'd carry one. But it does, and I have never needed one, even in Alaska in bear country.
Jim M