The last king of Westgate, the tyrant Verovan, supposedly had a legendary treasure hoard kept in a pocket realm of the Abyss that was accessible only via a magical bridge that extended out from a battlement of the northernmost tower of Castle Vhammos (one assumes the bridge was invisible), and required a key to open the portal (a key that is part of the badge of House Thalavar.
Now the key and the treasure hoard were lost forever in 1368 DR when the key was thrown through the aperture leading to the pocket realm (thereby preventing it from being opened from the outside).
That is all from the Cloak and Dagger web enhancement.
What is puzzling is that the worshippers of the Baneson are interested in the hoard because the pocket realm is supposedly in the home of Iyachtu Xvim's mother (a marillith i think).
Now the question is what else do we know of this hoard. Why is it linked to the Baneson's mother's realm.
Could it be that the hoard of King Verovan is actually the misappropriated hoard of Iyachtu Xvim from when he ruled Westgate (in which case what other secrets does Castle Vhammos/Xvim hide).
If so how did Verovan come to possess the key that opens the portal. Did he steal it from Xvim, find it by chance, perhaps Verovan and therefore Thistle Thalavar are descended from Xvim. The greenness of the feather is Xvim's favoured colour (although i'm not sure of the significance of the copper or feather to Xvim).
Anyone have any ideas, thoughts, or knowledge, etc?
Yup. The hoard plays a major part in the novel. The final battle actually takes place inside it, and there's a lot of exploration into what it is and how it came to be.
Doggedly converting 3e back to what D&D should be... Sigh... And now 4e as well.