From the legendary blue:
"The quest culminates in the earth-scorching execution of Deathwing himself and a shocking revelation about the true nature of the mission."
such as... kill whoever is pulling the strings behind Deathwing?
It says the execution of Deathwing himself, not the force behind him. My guess is that it is old-god related maybe DW and N'Zoth got drunk one night and.... gross. Woudl explain the draconic/tentacle style of the final version of the daggers.
The true nature of the mission, as in your mission given by the black dragon. The new black dragon is going to pull of a tweeeeeest at the end of the quest line I guess.