I always thought that taking the head off of a 19oz++ California style framing hammer, wrapping some leather around the head for comfort and attaching it to an appropriate length hickory or ash shaft would make an ideal defensive walking cane.
It wouldn't attract too much attention, and if it did, just mumble something about carpentry.....

I like this hammer head for the skull and crossbones logo :-)

http://www.hobbytool.com/browseprodu...ng-Hammer.html