Makeshift defensive weapons? Hmm, a scarf is a well known defensive weapon, especially if loaded with a small pocket of sand on the end(s).

Glass or plastic of suitable thickness can be used as an effective slashing/stabbing implement. There are also pens specifically made for self defense that are functional as pens.

Think outside of the box, and do a little market research, you will find a plethora of useful and relatively unrestricted items.