Justice is a fan-made global mod.

In reality, susceptibility and immunity to "words" can be viewed in different ways. 1) Evil factions (demons, undead, Dungeon) are vulnerable to Holy, while good factions (humans, mages, dwarves, Sylvan) are vulnerable to Unholy. Orcs are in the middle. 2) Children of Urgash and undead are vulnerable to Holy, while children of Ash, i.e., the rest, are vulnerable to Unholy. Orcs are again in the middle. 3) Those who practice Dark magic are vulnerable to Holy, while those who practice Light magic are vulnerable to Unholy. Orcs are neither here nor there. In my opinion, the second point is the most likely, so the original arrangement suits me perfectly.
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Of course, the Tuídhana elves are dark and evil, but they still worship the daughter of Ash and don't fit into the second point.
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It seems to me that demons simply cannot be vulnerable to both "words" according to all the points.