This is an odd style to have...I would imagine that lowering aggro is useful if you have another tank-type fighting alongside you, and you want to ultimately 'hand-off' a mob after doing a certain amount of damage...otherwise, as a tank who wants to simplify the healer's job, my preference is to use Plague and MAXIMIZE the aggro on myself.
Perhaps there's some fighting methods I'm missing?
Bari d'Hache
Assistant Smith
Pellinor, Midgard