Fear is pretty much a death sentence in hellfire. Admittedly it's been a long time since I took my lock through there, but I don't recall using fear at all in that place other than as an escape tactic. The mob density is WAY too high to even think about being fearing anything.
I'd recommend getting some outland greens off the AH before heading off to hellfire. At 58 the first few quests (before you get decent outland gear) will totally kick your *** if you're in old world greens/blues. Once you're in mostly outland gear you can drain tank just fine again..
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75 Rabbit/75 Sheep/75 Coeurl/75 Eft/75 Raptor/75 Hippogryph/75 Puk
75 Scorpion/75 Wamoura/75 Pixie/75 Peiste/64 Sabotender
51 Bird/41 Mandragora/40 Bee/37 Crawler/37 Bat
Items no one cares about: O
Missions no one cares about: O
Crafts no one cares about: O