The Accursed Keepsake has a small chance drop from every rare event boss in Icecrown. This item is an HD version of the old Scourge Invasion item Haunted Memento that invokes a Torghast Deadsoul ghost to follow you around!

Papa's Mint Condition Bag

This is one of the only 34-slot bags available in the game, the other one being Madman's Luggage available from The Mad Merchant in Legion Dalaran for 500,000. Thankfully, Bronjahm's bag is Unique, so you don't need to try and farm more than one per character!

Argent Commendations
Argent Commendation can be used to buy gear and other items from Quartermasters tied to the Scourge event. These tokens can be gathered from a variety of sources:
Sources
The main questline rewards a total of 18 Argent Commendation.
The quest  Nathanos Blightcaller rewards 5 Argent Commendation.
Completing all available dailies should reward a total of 17 Argent Commendation per day.
The daily  The Safety of Others unlocks from the beginning of the event, and rewards 5 Argent Commendation.
Icecrown dailies reward 3  Argent Commendation each. Some dailies are accessible from the beginning of the second week of the main questline, with the rest are unlocked with  Continued Effort after you complete the main questline. In total, four Icecrown dailies should be up every day.
Most Scourge enemies in Icecrown drop  Darkened Scourgestone and have a smaller chance to drop Pitch Black Scourgestone. Bosses drop multiple  Pitch Black Scourgestone. These can be turned in to Veteran Crusader Aliocha Segard for Argent Commendation.
Darkened Scourgestones rewards 1 Argent Commendation per every 25x  Darkened Scourgestone
Pitch Black Scourgestones rewards 3 Argent Commendation per every 25x Pitch Black Scourgestone.

Set up a set of 8 parts, a total of 120 Argent Commendations.
Reward 17 Argent Commendations (5+3+3+3+3) for 5 daily quests per day. If you only do daily quests for about 7 days, unlock a set of illusions.