I was on a galleon we had 4 and he was by himself. We were running a chest up a path from behind the outpost and he randomly came out of a bush and blunderbuss me. He then boarded our galleon and killed all of my teammates. He would sword through steps,floors, barrels, and poles. He then exploded a barrel and made us take heavy water. he camped mid level / below deck so we couldn't repair. He used blunderbuss and sword, and appeared to be hacking as he didn't die after multiple blunderbuss hits/swords. he also hit every single shot. he blocked multiple swings, then instantly hit us. Was insane.
My friend also said he ran into 2 other players the other day on plunder outpost. they killed him took his loot as well. Seems like this guy is getting around now and doing it for a long time.
Just be careful when you go to plunder outpost. Not sure why that outpost but he was waiting in a bush behind one of the huts.
between my brother and I we lost 4500-6000 worth of loot to this guy :(