I generally hang a knife off my shoulder strap about the height of the sternum strap on a carabiner along with a firestarter rod and other stuff..hang it through the gear strap to stop things rattling around(or leave it out and use it for bearbells..
).I like the knife to be a decent length but not heavy.Here's a couple examples on packs:
First has a magnesium bar(usually use wetfire though..magnesium is a new addition I haven't tried yet),firerod,knife,and small alcohol stove.
Second has magnesium bar,firerod,lightweight knife,and pepper spray for mountain goats,critters, and morons.Like I said,the straps have3/4" nylon with 2" long holes and things tuck across those..and things are easy to access when needed.I rarely need a screwdriver,pliers,tweezers,scissors,and other things.Overnight trips get a p38 opener if the knife doesn't have one.I hate looking for stuff when it's needed.
The blue carabiner is a timer(how long on the trail point to point),clock(+day,date),temperature,and countdown timer..turn the ring around the dial for different modes.