So it got recently revealed that Beledar is pretty much just a huge chunk of Azerite which throws out of the window the idea that it was a naaru on a ship, but what if (and this is the first theory) there is actually a naaru in there, trapped inside the crystal and the crystal is not from Azeroth but from another world with a soul that exploded and a naaru got stuck in one of the pieces and traveled through the universe and landed on Azeroth.
The other crazy theory is that Xalathat also came from the grand dark beyond in one of these crystal, arrived as a naaru in the times of the black empire, became a void entity and got trapped in the blade.
The other crazy theory is that Xalathat also came from the grand dark beyond in one of these crystal, arrived as a naaru in the times of the black empire, became a void entity and got trapped in the blade.