The headmaster's angry voice cut through the laughter like a knife on bear skin.
Answer:
mimic means to copy. Like if you copy someone's looks, that's mimicry
You can include more sophisticated words which enrich your work also make sure your work is aimed at an audience you think your book is for.
acting with strength and bravery
The word valiant comes from the Latin root valere which means strength. Valiant is often used to describe the characters of knights and other hero figures. Other words that are derived from the root valere are valor, valedictorian, valid, invalid. While someone who is acting valiant may feel pleasure or happiness, this is not the correct definition. Also people who are described as valiant rarely are described as behaving in a self-serving manner.