Penguinmagic.com sells the plastic appearing canes as well as disappearing canes if anyone wants to get one and experiment. The drill idea sounds like it has merit, but I'm stumped as to how you would get it to work. In a nutshell, these things are basically giant ribbon springs arranged with the tension toward extension or retraction. Currently, it is impossible to combine the two into one unit as far as I know. A small motor may be able to wind the spring the opposite direction thus making it easier for the blade to "fall" into a retraction, but I don't know. experimentation is in order, and I trashed my last appearing cane and am low on funds.
It most certainly wouldn't be suitable for anything more than extremely LIGHT dueling. By that, I mean if you put any force into a swing, you might as well knock two slinkys together. You'll spend the next three hours untangling them. For a concept prop, it's an interesting idea, but not for dueling. Polycarb may be a bit stronger, but I trashed my last cane just by leaning on it lightly, so that should give you an idea. And that was a METAL cane. The plastic versions are more forgiving when bent, but equally unstable.
Hope this helps.