My favorite is not one really built to be a weapon per se and likely more in the self defense category (I thought of putting this in the self defense link, but since I'm broadening the question to any martial arts weapon, including ones that are illegal to carry on the streets, I put it in General Martial Arts discussion) the Blackthorne walking stick. This was suggested to me by my self defense guru, who teaches the use of it and even has a video on the use of it as a self defense weapon. It is long, easy to use, and has knots on the wood which will break the skin of somebody hit with it, the loss of blood serving to weaken the attacker, and it is legal. I haven't walked around with it for a long time, but it comes in handy in certain situations, I keep mine near the door in my home just in case the person knocking on the door decides to attack for some reason.
What is your favorite martial arts weapon?
What is your favorite martial arts weapon?