Should you wish to do so, the following items are allowed in aircraft cabins and can be turned into weapons. This is a partial list, and I leave it to you to figure out how they could be used.

Pens
Pencils
Belts
Shoe laces
ANYTHING glass -- esp. bottles and compact mirrors
Paper clips
Plastic knife and/or fork and/or spoon
Clothing
Magazines and books
String
Diabetic syringes and glucose test kits
Wrist watch
Cassette tape or CD
Rings
Cell phones
Rubber bands
Asthma inhalers

and of course,

Your body, esp. your hands and feet, but also your head, knees, elbows, and hips.

So, as was stated way back in September, 2001, the best way to insure safety on an aircraft would be to strip the passengers naked and drug them unconscious, fly them that way to their destination, and revive and clothe them there.