Answer:
Simile or Comparison: it is a rhetorical figure that consists in comparing a real term with an imaginary one that resembles it in some quality.
Explanation:
The one that matilda describes pernilla as a warship walking around the room, is making her interlocutor see that pernilla is has a strong temperament and a rigid and dominant character, that he is alert, ready for war to ignite discord before any signs of alarm or suspicion.
