What is an example of irony in Act 2 of Romeo and Juliet?

In Act II, Scene 4, Mercutio is telling Benvolio about
Tybalt's abilities in fencing. He also reveals in his description of Tybalt, that he
fights with great precision. Mercutio compares Tybalt to a cat. Tybalt embodies the
personality traits of a cat: inquisitive, confrontational, precise and skillful. It is
ironic that Mercutio is describing Tybalt's ability to use a sword. Later in the play,
in Act III, Scene 1, Mercutio and Tybalt fight each other in a duel, and in an attempt
to stop the fight, Romeo jumps in front of them, and Mercutio is fatally stabbed by
Tybalt.