I've thought a lot about this title. If I remember, the next phrase Antony uses - Caesar and Antony are discussing making some kind of compromise with Pompey's forces - is "no mercy."

One of the things it took me a long time to realize was that, from the git-go after the Rubicon, Caesar made it clear there would be no proscriptions, no destruction of his political opponents in the Civil War - deliberately going opposite to the horrible memories people had of Sulla. Several sources agree that Pompey, on the other hand, and his crowd were PLANNING to proscribe if they won, to destroy every supporter of Caesar physically and/or financially.

Antony is taking the standard line here - war to the knife. Caesar blew everyone away by doing the opposite. It was very noble and, of course, it got him killed in the end. And because Caesar was killed when he was trying to be merciful, Octavian and Antony were ten times harsher when THEY finally came to total power.