Spiritual protection appears in many guises in dreams from images such as a cloak to a mist. It will depend on the type of protection needed – a cloak would suggest a closer, more intimate level than a mist, which is more ephemeral or disparate.
Psychological / emotional perspective: It is a natural reaction to need to protect ourselves from harm and for many people an emotional attack will cause us to dream of trying to find some sort of protection. When we feel that a principle or idea needs preserving we will often dream of protection of something.
Material aspects: When we have been made vulnerable in daily life our dreams will offer an image in order to help us deal with the problem.
The mind has a habit of imaging the necessary type of protection needed.