Guild Wars 2's Aetherblade Pirates come from the air, and they're the subject of intense speculation from the Lionsguard. The lore of the group isn't exactly revealed in the latest blog entry, but it should give anyone anxious for more pirate details some interesting food for thought.
According to the official Lionsguard report, the Aetherblade Pirates do not appear to associate with any existing pirate groups and refuse to give any details regarding their leadership. There's also reason to believe that the pirates are not actually responsible for the maintenance of their own ships, as those captured display no real knowledge of the working mechanisms behind these vessels. So it may be that they're simply a marauding force working at the behest of a more dangerous power, which may be an unpleasant thought indeed for Tyrian residents.