When I'm backpacking, I carry the Leatherman Squirt PS4 for the combination of pliers and scissors. The pliers get used to drive a heavy needle for gear repairs in the field. Just used them on the last trip to remove (screw driver), repair (pliers and scissors) and reinstall a blown wrist strap on my hiking poles. The scissors also get used for first aid and nails as others have described.

If cutting tasks were nothing more than than thread and foil packaging, this would be all that is needed. But for us, food often means meat and cheese or peanut butter. Not adverse to starting a fire if wood and local conditions allow. I find the Opinel 8 or 9 is great at both and carries well in the pocket.