For a sap, my brother recommends a sock and 4 size D batteries.
Yarn Harlot says you can take on knitting needles. Although everyone on the list said they’re not dangerous. (There are 251 comments on the blog entry!)
And remember that guy who pushed the stewardess around? They used duct tape to strap him in his seat. I’m taking duct tape to Orlando.
Good strong metal pens. My brother bought one for his airplane trips.
A gun would be good, but apparently those are against the rules. Oh well.