For the silent swordsman it would be cool if he had the silent silent no mi as it would extremely helpfull to captain jack but let´s get part by part said Jack the Ripper. 1 - Captain jack could manipulate the water to go faster within the Black Pearl. 2 - Water Radar , the captain Jack could basically control the flow of water to tell if there is some treasures or something in the water. 3 - Now why the silent silent fruit for the silent swordsman will be indispensable for the Captain Jack? Easy, because it wil help him greatly , how? Well very easy , 1 - The silent silent no mi is the nemesis of the gura gura no mi , how? well .When an object vibrates, it causes movement in surrounding air molecules. These molecules bump into the molecules close to them, causing them to vibrate as well. This makes them bump into more nearby air molecules. This “chain reaction” movement, called sound waves, keeps going until the molecules run out of energy. The fruit basically cancel all of that. 2 - Silent swordsman could "Silent" the connection with the devil fruit of the opponent for a few moments 3 - Silent swordsman could basically could speed up the ship with jack as he could "Silence" the sea. 4 - He could make a silence 'Slash' and that would make the slash more fast as the wind would not produce it´s force. 5 - Silent swordsman could be perfect for Iaido as quick sword drawing + silence is pretty strong. 6 - Silent Swordsman perfect assasin for the crew and intelligence officer.