These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
How weird is it that the magic Troxartas is using to hold the souls of the warriors he has defeated does nothing to stop those same warriors from plotting with Deathstalker to find the artifact that is trapping their souls to begin with?
Fridge Brilliance: The magic works on Literal Genie rules and doesn't stop the undead from taking other actions independently unless specifically told not to. i.e. Troxartas told them to bring Deathstalker back to his castle - he didn't specify that Deathstalker had to be dead first.
Also, why doesn't Deathstalker destroying the artifact cause the Warriors From Hell to just drop dead right there? They stay in the battle, fighting for the good guys.