In regards to dreams, a firebrand represents extreme passion. It can also signify a sense of urgency that one feels in their quest for something. For example, if someone dreamed about a firebrand that was being thrown from one place to another, this may represent someone who is deeply passionate about what they are doing.
Other possible examples of this might be when you dream about someone who passionately speaks to you of the need for a change or it could symbolize your own intense interest in something which is very difficult to attain.
A firebrand in dreams may also signify someone who needs to be encouraged and have their emotions supported. In some cases, it could represent political rivals trying to stir up trouble for the dreamer.