The items in this collection can all be found as corpse loot on mobs related to this quest in the zones listed unless noted differently below in the list of Items in this Collection.
When the collection is complete, you can turn it in to any Collector NPC for your reward and a very nice chunk of experience.
Items in this Collection
The pages are for a book entitled "Snuffing the Fireknight" and can be found in the following zones as chest drops from any mob in the respective zones (solo or heroic, they all have the same chance to drop):
Next, speak to Juna Crankfizz at the docks in the Butcherblock Mountains, at 636, 26, 588 . You must have the book in your inventory to get the quests from Juna. Tell her that you found a book regarding the Fourth Warrior, then speak to her three more times asking about the Leather, Metal and Silk sections of the cloak to receive the next three quests.