You point the redbeard out to the sailors. "That one, there! He is just about to cross the water! We must take him when he comes! He is one of their leaders!"
When the man with the scabbards carries himself across the water with the echo spell, he finds a crowd waiting for him. He is so surprised that he shouts the forbidden word again, to carry himself back to his vessel!
He is not alone in his retreat; your sailors have begun to turn the tide. The defeated pirates transport themselves back to their own ramships, vanishing from your decks.
But your enemies have lost many of their own sailors in the battle and cannot properly escape unless you permit them to retreat. Will you allow them to go?