Carry a hardwood cane and practice some half-staff (aka Tambo in Japanese Martial Arts) skills. If you do get cornered into whacking someone upside the head, a cane gives a better first impression than the (argueably concealed) edged weapon to people who will be making important decisions about what happens next after an unpleasantness (like police officers). Also, a good 36" stick has more reach than the 16 or 18" blade you might get from a sword cane....
FWIW, the preceeding opinion is brought to you by someone with training in western fencing and eastern half-staff but never having had to apply either.
Additional FWIW's: Thinking about it further, I own both and the sword canes are stored a lot less conveniently than the tambo. The tambo is about as convenient as one of my rapid access handguns. Also, I have never carried a sword-cane in public but have used a real cane on occasion... plus I "spotted" a sword-cane at about 30' once because it made a noise I recognized as the blade shifted in the shaft (I know that call was right because the weapon was being used in a stage play and my ex-wife, who was in the play, confirmed my hunch)....