Justice is a fan-made global mod.

2. The "Boiling Blood" ability grants three things:
1) Vulnerability to Unholy
2) Vulnerability to Holy
3) Vulnerability to Blood Rage effects on Horde units

Wyverns (without Boiling Blood) are indeed immune to Holy, but still vulnerable to Unholy.
Therefore, it should be:
1) All are vulnerable to Unholy, except creatures with Undead and Demon abilities.
2) All with Undead, Demon, and Blood abilities are vulnerable to Holy.