Recognize a relative clause when you see one. A relative clause—also called an adjective or adjectival clause—will meet three requirements. First, it will contain a subject and verb. Next, it will begin with a relative pronoun [who, whom, whose, that, or which] or a relative adverb [when, where, or why].
Poetry theme is the word choice
Answer: the denotation of fierceness is the word itself.
Explanation: here's a definition of fierceness: violently hostile or aggressive in temperament, given to fighting or killing, or pugnacious.