You can kill people with tweezers easily, just go stabbing everyone in the eye/throat like madness, after using them to cut/rip the seat belt to have a longer range weapon to hit people, use the pillow as a 'shield' to soften/dodge punches/strikes. Tho you can kill people with your hands... If you're creative enough you can kill people by dropping Cesium metal, Rubidium metal into the toilets, causing the plane to get damaged.

Get bored = figure millions of ways to kill people in the current area. '-'