The trick here is, buy a cane that doubles as a weapon, not a weapon that doubles as a cane. The length should be from the ground to where your hand normally hangs to so you don't have to bend over to use it or bend your arm too much because it's too long. Get a nice rattan or cheap wood cane with a crook that barely fits around your neck, UNcomfortably. Get one that's the right length for you to use it as a cane. Then get instruction on how to use it as a weapon from a qualified instructor.

I've bought really expensive canes from canemasters and they're nice. But, the one I bought for $3.95 at the drugstore is the one I use now. The "combat" canes they sell are too heavy and the crook is too forgiving. If you must spend a bunch of money cuz it's burning a whole in you're pocket, you can get a nice hickory one from them. But, don't get the full sized one. They have one labled for women that's smaller and actually more practical for use.
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There are no PERFECT techniques, only perfect execution for the situation at hand. ~Corwin