Originally posted by Tohatchi NM
Cane is a good idea.
Waterbottle is also a good idea. I would choose one of the Lexan (hard, clear plastic) Nalgene brand - about $8. 1 Liter would be a bit slow if full, so you could go down to a 1/2 Liter which would also be more concealable. Tough loop on the top for swinging purposes. They're also available in colors - who would thing you're going to beat them with a pink waterbottle? You'd have to be careful, though. A well-placed head shot from a reasonable strong person could be lethal.
A carabiner - the clips you see everyone with their keys on, started out as climbing gear - would make decent knuckles. You'd have to be a bit choosy to find one that fit your hand (I have skinny fingers) and have a broad finger contact area so you don't break your fingers, too. Go to a camping store that sells climbing gear, they should have a dozen or more different models to choose from. Innocuous looking because they're everywhere these days.
Finally, if you want a purpose-built tool, good stuff has been said about the Spyderco Gunting, though I don't own one myself. There is an edge-less version available - the CRIMPT - which has all the sharp points of the regular version, but the blade is blunted. (CRIMPT is only available directly from the designer, so far as I know) There is also a blunted Training model which has some of the handle points rounded off, but is still servicable as a striking/trapping device. This may have a learning curve, so if you need it NOW it might not be the best option. Gunting + tape training system would probably run $150 -$200 depending on which tapes you got and if you could find one used. Our favorite khuk user (Saint) Jim is also a rabid Guntaholic. Howard Wallace, also an HI fan, posted a review of his edged Gunting on the Spyderco forum, saying it was a great utility knife.
Hope this helps. As Sarge says, keep your head on a swivel. Don't get yourself or anyone else into unnecessary trouble.