...You know that Nergal is the God of War AND Death aswell as the Lord of the Underworld.
Orcs aren't religious in most of the Lores... at best they have a deep connection to the Elements/Spirits but they are no gods, nor worshiped.
True, Nergal from IRL myth is a war God but there has been no mention of him being so in PQ. Until Tink says there is another or that Nergal is the war god, I will only refer to them as the "Lord of The Underworld". Pagan gods are public domain so Tink can separate or merge them as he sees fit really. Anyway Lord of War was just an idea lol. In the same manner as there is a separate Lord of Death in this world so I wouldn't put too much stock in the myths, Tink can tweak, & has Tweaked, whatever he likes to make it fit his setting.
Orcs are the only race Tolkin created that did not get any actual culture built to them. It has been others who have created there culture later on. Why cant the PQ Orcs worship a war god. I mean they do in D&D & they worship a war daedra in Elder Scrolls.
That doesn't seem to fit the Lore... Werebtas and Spiders were not cursed, but evolved into these forms... there isn't much known about Werewolfs, but if anything I think they once were Victims of Witches nd witchers but became their own people as the Werewolfs you encounter don't change shape dureing the day or night
For me this is a hazy subject as there is no mention of where they come from. But I will say this, the only true Were-Beasts i have seen i this setting (by my own knowladge) is were-wolves.
Bat Creatures
I dont think these are "were-bats" as even Erevi calls them Bat Creatures. I think they are there own species of anthro-bats that live in caves. Yes they are obviously inspired by the "Were-Bat" monster girls but I dont think they are the same beings. These are unique to the world of PQ by being a stand alone species. This is coupled with the fact they lay eggs when bats should birth live young.
"Were-Spiders"
Venomina & her ancestors are the descendents of a witch mating with giant spiders while in spider form. The name "were-spider" is only used once by Erevi when she is trying to wrap her head around what u told her. They technically are a new & never before seen species. Also they remind me more of the Jorogumo of Japanese folklore (monsterous spiders that turn into sexy women so that can lure men into there lair & eat them). Again I wouldn't say she was a TRUE were-creature because only a queen can do it & all her young are just normal giant spiders. I'm not saying she INST a were-spider, I'm just saying she might be a unique brand of were-creature.
Were-wolves
The only were-wolf we see (that hasent been corrupted into a Plague-wolf) is the one that cucks us with Mia. He appears as a beast even in broad daylight do ether were-wolves become trapped once they have changed or they are there own species of unique monsters. This is not explained so it was me trying to think of some reason that could be linked into the lore of the setting.
I mean, when she is added you probably wouldn't call the cow girl a "were-cow" at best she is a female minotaur or a holstaur. The bat creatures appear more like Beastfolk & the "were-spiders" are a magical anomaly that follows some were-beast rules.
I'm not saying you're wrong just that I know that hunt gods are sometimes associated with shapeshifting/were-beasts in myth so it was an idea. Could be witch curses, god "gifts", ceremonial or magical Cross-Breeding lol