Trophy description - Perform 5 air assassinations from a swinging rope

Trophy - Bronze

Air assassinations from swinging ropes can only be performed when boarding a ship. You must first weaken the ship to within the red zone of its health bar and then pull up alongside to board and hold Circle. There are 4 ropes on the Experto Crede in which you can use to swing over to the ship in which you are boarding. The ropes are located on either side of the ship at the bow and the stern. To swing from them just hold R1 nearby. Before swinging try and align yourself with an enemy on the other ship to make the assassination easier. Once you are swinging watch for the assassination prompt in the top right corner next to the Square button. Once it appears quickly press square to perform an air assassination. Once you have successfully performed 5 air assassination from a swinging rope, the trophy will unlock.

The below video by the The Box Bros portrays the entire process of boarding a ship and performing air assassinations.