"Answers" mark 3.

[Cassandaria]

Now, the Warriors of Darkness are not meant to be "Evil", mind you. They're just meant to be folks who, much like the Warriors of Light fight off the forces of darkness to prevent them from swallowing the world, the Warriors of Darkness once fought off the forces of light to prevent them from swallowing the world, both trying, albeit ignorant of their true purpose, to keep the world in balance.

For those who need more context on the Warriors of Darkness: http://finalfantasy.wikia.com/wiki/Warriors_of_Darkness

The warriors of Darkness actually combated the light. As Light and Dark are simply powers that balance each other out, neither being evil, the fact of the matter is, it's how they are used that dictates what kind of warrior comes about. The warriors of light combat the darkness, the warriors of darkness combat the light. This would fit in with the fact we have seen another crystal, similar to the one of light, but in darkness. So it IS highly possible, with the addition of the crystal tower that part of FF3's storyline will seep into our world here and I would not mind at all.