I don't know where to put this, as it relates to guns but isn't about balance. Move it wherever if you'd like.
Why it is bad
Because its exactly the same as the lore for argent peacemaker, but centered around fiends instead of fiends:
Argent Peacemaker:
"An ancient handgun forged from sun silver. Its bullets serve as ushers for those that refuse to leave this world."
Gilded Griffen:
"A beautiful pistol named after a great, noble beast. It's* golden frame was believed to provide light within the impenetrable darkness of the Underworld."
So let me get this straight. The antigua gun can be upgraded into a positively driven, destroyer of evil, a maligned, hell bent variant, or a positively driven, destroyer of evil. That kind of destroys the dichotomy that was established before, whereby you had to choose between good or evil, almost like picking a side. I know its silly, but that was kind of awesome and I really appreciated it from you guys.
*And yes, the "It's" was used in the description on the testing server. I.E. "It is golden frame was..."
What to change it to
You gotta add to the story a bit with this! Find some kind of middle ground. The third line could easily represent some kind of grey area, or even just abstaining from religion on the whole.
Another thought is that the model is golden, and shares much in common with another weapon- the wild hunting blade. Why not make it have to do with beasts?
An example of the above:
Raptor- "An ancient pistol crafted from the bones of beasts. Its owners were said to have been driven from their homelands and forced into a life of solitude by angels, left to fend for themselves."
Gilded Griffin- "A beautiful pistol originally crafted from the gold encrusted remains of beasts. Its intended purpose was to fight off invaders from the Underworld while surviving in the wilds."
This makes it very clear that it wasn't the "good guys" that made the weapon, but some party in between. Something like this, would be a lot more magical in my eyes.
I find it weird that it's called the 'Gilded Griffin' when the creatures on the top and bottom of the barrel look more like dragons than griffins. They even share the design of the Drakon sprite..