I've never really had to use a weapon, so I cant say what would definately work... I'll have a crack anywhat.
Obvious
Keys
Pens
Pool Cue
Bottle
Ash Tray
Not so obvious
Jacket (strangling, blocking, distraction)
Aerosol (spray in the eyes, combine with a lighter? lol)
Rocks/Tiles (throwing , possibly used as stabbing weapon.. tiles are sharp)
Sand/dirt (distraction)
.357 Revolver (uses atm unknown, will continue to think

)
I've also wondered about the use of yelling. Like, screaming something just plain weird at the top of your lungs to confuse your attacker and possibly put them off? ( Yes, I'm aware it is not a weapon, but please bare with me)
Attacker: You made me spill my drink, what the hell?
(attacker shoves defender to provoke violent reaction)
Defender: MY LEFT LEG IS ON FIRE, PLEASE PUT SOME ICE CREAM ON IT BECAUSE I AM THE KING OF LEMON PEPPERED CHICKEN!!!
Attacker: Ahh, okayy ... get away from me..
Situation difused
