Just to add a little to the discussion:

Very well equipped warrior in raid buffs: ~7000hp (not the most uber, but that is really good HP still).
Epic pet HP: ~4000hp (by some estimates)


Duel wielding: For a warrior to tear through that, they'd have to hit them about 100 times (say median hit is around 40, sometimes more, sometimes less).

On the damage shield alone, they would take 5500HP of damage to a mage epic pet (assuming no pet regen, but the pet can regenerate fairly well). Even if the pet did not fight back at all, and just stood there, it would almost win. The damage shield is not really dispellable, as the pet just puts it back on.

Add the procs, spells, and melee to it, and it would chew duel wielders up, if not kill them outright.

A really good 2-hander would be the only way to handle that monster, and even then the stuns would hurt quite a bit (missed swings).

(I've seen Cielo's epic pet in action, it is the most powerful level 49 I've ever seen :)