Answer:
The sergeant meant that Macbeth and Banquo were extremely violent in battles.
Explanation:
The figurative language is found in the line "The cannons overcharged with double cracks." This line presents a metaphor that compares Macbeth and Banguo to the form of combat that this type of cannon presents. With this, the sergeant means that these two men are extremely violent in their battles and that they stand in a powerful and destructive way in front of their enemies.
