These sentimental items are one per instance and can be done in any order.
There is only one item that drops off the body of the final boss. If there is more than one channeler in the group that is on this part of the quest, only one will be able to loot the item for a quest update.
Return to Lord Nagafen
Consult the necromancers of Paineel. Letter on table at ( 1652, -265, 3176 ) Copy/waypoint 1652, -265, 3176
Kill the dragon construct on the top level of the rat cave of Sundered Frontier ( 965, -191, 3369 ) Copy/waypoint 965, -191, 3369, he can also spawn in one of the other passageways in the same area.
Has tons of HP, it is recommended to bring at least some DPS with you to help burn it down
Go back to secret lab in Paineel, it's on fire and you will be attacked by a construct
Pick up the book on the desk in the back of the room
This step requires having completed the Dark Mail Gauntlets heritage quest, and be wearing them in order to read the book
Defeat Ryizz in a special instance of Stratum
This is a solo instance with a Very difficult fight and no mercenary is allowed. You will need to adjust your AA spec and conduits for maximum individual survivability.
Pull the named into the middle of the room. You do not DPS it, but debuff it whenever you have a chance.
An enslaved npc will spawn every so often, ignore the name and destroy the add.
When a sphere spawns (there are different versions, arcane, elemental, noxious and dark), immediately change targets to the sphere and destroy it.
The key for this fight is to survive for roughly 6 minutes (+/- 15s). After the 6 minute mark, the mob will have 15 "ticks" before it dies. This will update your quest.
It should be noted that the name will do considerably more damage with each "tick", so do your best to save emergencies for use towards the end of the fight. My suggestion is to make two macros, that saves you from lots of tabbing around and wasted time: