Souldiers

So for this one you need to get all skills for every character. Which means you have to beat the dark sword on each character. Now if this doesn't unlock for you naturally there is a trick I suggest you do to make it pop. Whenever u play this game, never take it out of quick resume. For some reason my game was always deleting my progress towards achievements whenever I closed the game down completely. So if you're going for this, never take it out of quick resume