Carry a hanbo, ehem, I mean a walking stick, a folding knife, a piece of rope, shuriken if they are legal in your area, metsubushi (which could be in the form of pepper spray, or even a high intensity flashlight at night), a taser, or whatever other weapon you feel comfortable with. I don't know where you are, but in California, which has extremely strict self defense laws, you are allowed to use a weapon against an attacker, even if they are unarmed, as long as you don't continue to wale on them after the threat has been removed.
Whoops, should've checked before I spoke...now I see you're in WI. but it doesn't make a difference cause I have no idea what the laws are there...