This excerpt shows a tone of admiration through all of the words the narrator uses to describe the subject. He says they are "fierce as a dog" and "cunning as a savage". Fierce and cunning are two words that seem admirable to the narrator. The word "rebuilding" at the end also shows admiration, as the subject keeps rebuilding after things have been broken down.
A metaphor is a way of describing something by saying it is something else. This technique should be familiar to you as you will have studied it at 3rd level.
