You can always try the religious zealot ploy. Mount a large cross on your rear rack and constantly yell your favorite bible passeges. Most people will stay away. Wearing robes is a plus.

Seriously, changing your route is the best option. If you must carry something, use pepper spray. Most areas will not prosecute for pepper spray when used as a defensive weapon. Batons, bats and similar items will only cause you grief from the law..