All airlines have a flyer that lists the prohibited items on board the plane. That is to help you avoid the delay of inspections in the security check. First in the list are deadly weapons, of course, followed by pointed objects that can be used in place of a knife. And lately, I have known that e-cigarettes are also prohibited mainly because of its battery. Do you wonder why water bottle is prohibited in the security check but later you can buy bottled water in the store in the boarding area? Staff in the security check would confiscate your drinking bottle. But the plane allows drinking bottle that you bought there.