Paglth'an is the region directly to the south-east of Thanalan which is pretty much deep amalj'aa territory (dialogue in 1.0 stated the amal'jaa stronghold Zaha'rak and the Bowl of Embers was actually in Paglth'an not Thanalan, but I think that was since retconned), so I presume it has something to do with the amal'jaa (fitting, given the amalj'aa were the first to summon a Primal and their race is now pretty much entirelly tempered by said Primal save for a small group of rebels who made up the Brotherhood of Ash. It might involve trying to cure said amalj'aa of their tempering).

As for Diamond Weapon, I wonder if that will end by having a hole blasted through it by a giant cannon?