As a student of various martial arts, including fencing and knife fighting, I am of the opinion that a walking stick or cane beats a knife every time. It has more reach, delivers more immediate 'target' incapacitation and is already in your hand. (It also is much easier to explain to local LEOs than a 9" sub-hilt fighter.) There is an old story about an English quarter-staff master who killed several Spanish swordsmen in a 'gentlemanly contest' (while a captive) during the Elizabethan-era war between their respective countries. I dare say Spanish swordsmen of that day were probably better fighters than most modern gang-bangers or would-be Jim Bowie types.

It is a good idea, however, to be able to use a knife properly, if that's all you have. I would place 'combat' suitability near the bottom of the list of required attributes for a knife.