This quest was marked obsolete by Blizzard and cannot be obtained or completed.
Use the Divination Scryer in the heart of the Great Ossuary's basement in the Scholomance. Doing so will bring forth the spirits you must judge. Defeating these spirits will summon forth Death Knight Darkreaver. Defeat him and reclaim the lost soul of the fallen charger.
Give the Charger's Redeemed Soul and the Blessed Enchanted Barding to Darkreaver's Fallen Charger.
Take this satchel - in it are the items you will need for your task.
Use the divination scryer in the heart of the Great Ossuary's basement to bring forth accursed spirits that must be judged. Use your judgments wisely during this trial - they will prove more potent than you realize. After the spirits, the death knight will appear; defeat him and reclaim the lost soul of the charger. Only then <name>, will you be able to redeem it and place your barding upon your new steed!