It looks as if historical accuracy is something that really matters to Ubisoft, and to show that, they have made a brand new video showing off the various types of in-game weapons you'll be able to get in Assassins' Creed IV: Black Flag.
On top of this, the video gives a quick preview of the port of Genoa, a location that will probably play an important part in the story.
The video includes a rather energetic historical weapons expert discussing the variety of weapons available to the pirates at the time. He makes a mention of guns, knives, swords and even grenades, but also talks about psychological warfare, a method used by pirates to scare and intimidate their enemies into surrender.
The whole concept behind pirates is a scary one, and if you were out at sea, pirates would be the worst thing you could bump into. It will be interesting to see what kind of options we have open to enable us to scare our enemies into submission.
Along with psychological warfare, knives, swords, cannons and grenades, we should be able to have completely dynamic and ultimately epic naval warfare in AC4.
If you're into learning about the historical nature of games and movies, I'd suggest watching the video as there is some interesting stuff to learn about the background of the game and get an idea of the kinds of combat that'll be introduced to Assassins' Creed IV: Black Flag.