Well, the entire church of Aeos, including the High Elders and the most suspicious inquisitors, have all concluded that the skeletal St. Aleax is the real one. Some members of the Knights of the Emerald Chapel have disagreed, and have been riven from the church thereby.
Aleax (the sword) was found in the hoard of a dracolich's lair. It had been there for hundreds of years, and could no longer remember its origins; nevertheless, it did remember its identity. I think its pretty clear that the sword has true paladin abilities; it can lay on hilt and detect evil, for instance.
The original expedition to the White Kingdom was undertaken by Aleax, Morak of Calphas, and others. The story isn't well known; according to a legend lore and what the skeletal St. Aleax told Mara, their group had the ghouls trapped in an area that served as the only access point from the ghoul-controlled caverns to the rest of the Underdark. If they could have held them there, the ghouls would have soon run out of both victims and boltholes. When it became clear that they were losing the battle, Morak brought down the ceiling of the cavern. He killed himself and his entire party, along with many thousands of undead, sealing them into a stony prison for centuries. They eventually carved their way out, though, and have advanced through the underdark since. For some time their progress was checked by a city of mind flayers. Ironically, Nolin and the Defenders had a cubic gate that led to this city, and they sold rights of access to a rrakma (hunting party) of Sigilian githzerai who proceeded to lay waste to the illithids. By the time the githzerai departed for their own plane, the mind flayers were no longer strong enough to hold back the ghouls, and they advanced once again.
We played last night, and saw some truly spectacular role playing on everyone's part - especially Malachite's. I'll finish Mara's conversation with St. Aleax, and write up Malachite's, this weekend. Look for an update on Monday!