One of the better options for self defense is a cane. It's useful for walking, legal to carry anywhere, and doesn't require licenses or anything special. Here's a collection of videos on canes for self-defense:
If you only learn one move, this is the one to know:
https://www.youtube.com/watch?v=bpjBwJmBaT8
https://www.youtube.com/watch?v=pULOnrVEmGs
https://www.youtube.com/watch?v=Zo1G1cpOaBQ
