Here are a couple of videos of Premier_N7 (author) taking down some of the ACIV Legendary Ships
Assassin’s Creed IV: Black Flag Legendary Ship battle with El Impoluto. It wasn’t pretty. The beginning and the end are the ugliest, but I made it happen. Hope you enjoy.
Assassin’s Creed IV: Black Flag Legendary Ship battle with Royal Sovereign & HMS Fearless. Got some bad luck with the waves on a couple of ram tries that left me high and dry. Otherwise, pretty clean cut.