Sunglasses in a survival situation may seem like an unneeded item for some, and a frivolous extra for others, but I think taking a pair of sunglasses, especially in your Urban Survival Kit is a good idea, and not just to block the sun.
They say the eyes are the window to the soul. While that sounds like a cliche romantic line, there is some truth to that and it might just save you in a survival situation.
For example, do you ever wonder why Law Enforcement Officers almost ALWAYS wear sunglasses? It isn’t because they have sensitive eyes. Sunglasses put you in a position of power over someone that does not have them. Being able to look into someones eyes gives you a lot of insight into what they are feeling and thinking.
Think about how much you can read from a person’s eyes. Are they scared? Are they thinking? Are they looking at what they are thinking about? Are they looking where they are going next?
Imagine yourself as a police officer for a moment. As the officer you come up on a situation you are unsure of, and are somewhat nervous. By having on sunglasses you hide an important part of your body language that might accidentally display fear to someone who does not need to see it. By covering your eyes you maintain the tactical advantage of hiding your fear.
Now imagine yourself as the civilian. The officer approaches and you cannot see his eyes. You cannot read what he is thinking but you can imagine what he is capable of. Not being able to read him creates uncertainty, which means he has the advantage.
Can you think how this might be useful in a survival scenario? Especially in an urban environment where you are likely to encounter lots of people (and you might not be able to display real firepower), any tactical advantage you can gain immediately plays to your survival possibilities. At first contact you are immediately in a position of power, if only on the subconscious level of the other person. (Which can be the most powerful way.)
A word of warning: There is a flip side to this power. Covering your eyes with sunglasses also dehumanizes you. It might make it easier for someone to justify taking advantage of you in any number of ways. I am not saying you should use sunglasses to intimate everyone you meet, in fact often you shouldn’t, but having them gives you options. You get to chose to display this body language, as well as when. You get to analyze the opposition before showing your hand.