Well said Bouncer. I was going to counter AS Flyer's failed reasoning but really everything has now been said.
The following is a short list off the top of my head of things that can be used to hijack a plane more easily than cigar cutters, nail clippers or even box cutters (although a hijacking is now near impossible now that we are wise to the true purpose):

carry on luggage handles
some shoes and boots
collapsable roller doodads
pens
pencils
computers (heavy, blunt objects)
cell phones
some heavy jewlery (rings, chanins)
rolled up sky mall magazines
forks (non-plastic)
human feet
human legs
human hands
human fingers
human teeth
beverage glasses
keys
canes
seat belts (swinging that demo seatbelt extention around will make an extremely effective weapon)
pant belts (same reason)