From WoWWiki

The title of Hand of A'dal is obtainable as of Patch 2.4.0 to players who complete, or have completed, the attunement quests for Mount Hyjal (The Vials of Eternity) and Black Temple ([Medallion of Karabor]). Like Champion of the Naaru (the other attunement reward title), this will appear after the player's name, so it will appear something like this:

<Name>, Hand of A'dal

It is most probable that this title will be deactivated after players can level above 70 in the expansion pack Wrath of the Lich King to avoid easy access at higher levels.

Patches and hotfixes

Patch 2.4.0 (3/25/08): Players who have completed the attunement quests for Black Temple and Hyjal will be granted the title of "Hand of A'dal".

Titles
Arena	Challenger • Duelist • Gladiator • Rival
Battlegrounds	Conqueror • Justicar
Miscellaneous	Scarab Lord • Champion of the Naaru • Hand of A'dal • of the Shattered Sun