Do you know martial arts? If not, the weapons that you intend to carry and wield wont do you any good either....
If you do martial arts a metal pen is sufficeint to incapcitate the guy in a life and death emergency, otherwise just give the robber your fucking money..its a whole lot easier and yo can claim insurance for it. Do not escalate a simple roberry into a full fledge fight invoving weapons...the moment that you present your blade to the robber, you make him more determine to kill you and on the other hand the is no other way for you to get out of it unless you run or you have to the same..cut him down..legalities will catch up with you..pocesssion of concealed weapons, causing grivieous harm yada yada yada..not worth all the shit..