It might just be something like: Withers is *actually* Jergal!
That's something they'd want to wait for folks to know, and it was a big speculation point back around day one.
Then the Grand Arbiter he mentions is Ao, which makes sense. But if he supports us at the behest of Ao himself, that's also an imposant plot that should live up to the rest of the implementation. That would be a very high claim from Larian, against which they then have to be measured themselves. I mean it's a strange feeling to somehow be in the favor of not just any god, but Ao himself. Very bold.