I know this is an old thread, but nonetheless I'd like to shine a light onto it.
So the only purpose of the crystals is to spawn the bosses. In Felucca these bosses have guaranteed loot:
The boss of level 1 is a quartz elemental. To summon him you need 10 dungeon points, so 10 dungeon shame crystals. His loot is a quartz grit.
The boss of level 2 is a flame elemental. To summon him you need 20 dungeon points, so 20 dungeon shame crystals. His loot is corrosive ash.
The boss of level 3 is a wind elemental. To summon him you need 30 dungeon points, so 30 dungeon shame crystals. His loot is cursed oil.
Now the quartz grit, corrosive ash and cursed oil can be combined and they give a Whetstone of Enervation. (Those sell on ATL for 4m each)
This Whetstone can be used on exceptional crafted weapns to remove the DI those weapons automatically have, and thus opening another slot to imbue another mod.
Up The Irons
Henzy
Lord of The Ruskin Arms on Drachenfels