I sometimes carry an Irish blackthorn walking stick. It has the advantage of being legal everywhere, even on airplanes, and raises no eyebrows even when taken into a courtroom or a house of worship. Also, if I should need it, it's already in my hand.
There are some excellent videos available on the use of walking sticks for defense; it's not used as one would expect, and is more effective against knife attacks and multiple attackers than anything other than a gun. My own stick still has thorn-stubs up and down its length--even better.