In re appearing to be armed: A cane seems like the most reasonable choice, and even that has some social costs.
I know someone who has intermittent hip problems, and is intermittently hassled by random strangers because she doesn't always look as though she needs it.
When people talk about self-defense, they tend to concentrate on how to physically defend yourself. But the best way to avoid getting hurt is to avoid being attacked in the first place. Here are some suggestions:
What are some other easy measures that people can take to make themselves less of a likely target?