Guilder
09-22-2016

Obtained through mugging Captain Jack Sparrow. R20 plunder skill and a bit of rum recommended before the attempt.

Actually, there seem to be two versions of this weapon. One is dropped by red and orange Ganador Edward Teach (18 century Phase 3), the other comes from a 3 entry sewing/handicrafts only MA related to Port Royal 17th Century phase 4 recipes, which can be performed in Port Royal or through Aide Production (if you have an Aide whose ranks are high enough to do the recipe, that is). The MA items are:

Pirate's Boots
Tortuga Pirates
Buccaneer's Dress

You can collect your MA reward from John Dee. While this may not be the strongest weapon in the game, it does have a very nice look to it.

Source:

gvo.gamedb.info/wiki/?Ganador/Special
gvo.gamedb.info/wiki/?MemorialAlbum/Item1 (G.T. "Costume culture of the Caribbean Pirates")

Blake.C
03-03-2018

There's also one that can be obtained from the The Whydah shipwreck. Similar stats but carries +1 to Shipbuilding and +2 to Tactics