Tanking AOE packs as a gladiator reminds me a lot now of the original Vanilla WoW where you had to tab-sunder all mobs between limited AOE. The trick to AOE tanking as a glad is to play "Spin the Plates" with the enmity bars of each target. Usually I'll shield lob the primary target and then do between 1 and 3 flashes on the group when it reaches me (usually 2). I'll then do a Fast -> Savage -> Rage combo on the first mob. Then the trick is to tab between targets and see which ones are close to losing threat, usually to the healer. Rage of Halone is your highest threat move by a mile, and so I usually end up doing my Fast/Savage/Rage combo whilst cycling between mobs, and usually with the Halone on the primary target being DPSed. You can flash every few rotations but flash is noticeably less threat on a mob than doing a Savage/Rage.

Too many glads rely on Flash Spam. Rage of Halone and Savage Blade are your highest threat moves. Rotate them throughout the mob pack.