Yes, you said where it was. I will hide it, but it is not secret i believe.
It is inside the Crystal in Ahrenthrôk , so it seems it will be difficult to get there.
Soul sword is too powerful to play games with, i suppose. Maybe City od Dead, or maybe some players can get interest things in the Guardian Mind.
I always wanted that some GM made a game to capture a Thalan, it will be a game sort of a thriller movie. If i remember correctly the dyari discovered a chamber with 13 seats that some people (probably K'ta'viir) used as a prison for Thalan. Discovering how to trap them will be a good quest for some of the "annexed" realms of the Alliance. We know a lot about the regular troops of the Alliance (Kal'cha and Jenaar), so fights, intrigue , tension and confusion is provided by these background. Also it could be nice game for a small group.
Everything about Voriig is also very cool.