Presumably he means may the sword of Christ never mete out justice
According to a Catholic tradition today is known as Divine Mercy Sunday
I've just come across it but here are some phrases regarding the event reported to have been given by the apparition of Jesus:
"Let all mankind recognize My unfathomable mercy. It is a sign for the end times; after it will come the day of justice."
"Souls perish in spite of My bitter Passion. I am giving them the last hope of salvation; that is, the Feast of My Mercy. If they will not adore My mercy, they will perish for all eternity… tell souls about this great mercy of Mine, because the awful day, the day of My justice, is near."
Food for thought