Scimitars came from the ninth century from the Middle-East, but this game is around the 16th century. Fortunately, the Persians made scimitars popular in the 16th century, so the story should be more like this:
Across the far-away lands in a place called Europe, an E.I.T.C weapon shipment arrived in the Caribbean that introduced a new type of weapon to the pirates: The Scimitar. Unfortunately for the E.I.T.C fleet that was bringing the shipment, The Black Pearl attacked the fleet and sunk them to Davy Jones' Locker. The Scimitars were all lost except five: The Poisoned Scimitar, Venomous Scimitar, Assassin's Scimitar, Master Assassin's Scimitar, and Sultan's Scimitar. These five scimitars were sent to five different places -- The Poisoned Scimitar to Tortuga in the possession of Captain Jack Sparrow; The Venomous Scimitar to Rumrunner's Island in the possession of Bastien Craven; The Assassin's Scimitar sent to a deep quarry in Padres Del Fuego to Neban The Silent; The Master Assassin's Scimitar sent to a powerful Thrall Captain on Isla Tormenta; and the Sultan's Scimitar was stolen by the legendary El Patron. It is up to the pirates to retrieve these five new scimitars from these locations.
(This would be good because it would allow five new missions to be added for the scimitars, and it would be more historically accurate.)