Read the excerpt from act 5, scene 1, of Julius Caesar.

CASSIUS. Now, most noble Brutus,
The gods today stand friendly, that we may,
Lovers in peace, lead on our days to age.
But since the affairs of men rest still incertain,
Let’s reason with the worst that may befall.
If we do lose this battle, then is this
The very last time we shall speak together:
What are you then determinèd to do?

What does Cassius’s description of Brutus as noble rather than the synonym aristocratic tell us about his feelings toward Brutus?

Using aristocratic would be a compliment while noble has become a description that includes sarcasm.
Using noble shows how motivated both Brutus and Cassius are by a love of peace.
Using aristocratic would be insulting to Brutus while noble suggests the positive qualities Cassius sees in him such as dignity, generosity, and compassion.
Using noble is a term of endearment and great respect between longtime loyal friends where aristocratic would be impersonal.

This is a figure of speech that makes use of words and situations which are opposite in meaning or are unintended to what a person is saying or a given situation.

Hence, we can see that based on Cassius' description of Brutus, we can see that by calling him noble, he is using sarcasm to describe him because he does not think he is noble.