Enmity, I believe, is the stat that determines when the mob decides that it's your turn to get smacked around. Reducing enmity is basically the same thing as reducing aggro....sort of an "anti-'voke".
Since it's latent, I would assume that it only works after you've taken a few hits, and your HP drops into the yellow. Someone else may be able to clarify that further.
On that note...is -2 enmity really enough to make a noticeable difference?
My understanding is your enmity is a set number, and all actions to a mob or PC with the hate of a mob get enmity. Each action has a certain number for hate, which is multiplied by your enmity. I'm pretty sure -2 would make a very noticeable difference, I've read blink tanks raving about enmity +4 through a pair of earrings. When this latent effect kicks in, it won't drop your current hate level for the mob, just the hate produced by your actions from that point on. This is how I understand enmity, but I could be wrong.
I think Stouter is about right. Enmity + anything or - anything will make a monumental difference. I have talked to a few WARs with AF gear, and they say that even without the full set on (it has a TON of Enmity +), PLDs in their parties don't stand a chance to hold aggro. Looking at how hard a RNG hits, anything that can reduce the chance of them pulling aggro is a good thing. However, that said, I really doubt it can replace the utility of a good +1 bonecraft ring that gives + racc.
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Formerly Valhallodin of HouseAtreides on Caitsith Caitsith - San d'Oria - 75SAM - 75RNG - 65WAR - 45THF - 44PLD - 40NIN - 36BLU - 30DRG
all that takes is a quick armor swap macro, once you're in the yellow that is. This way you can still attack it while the tank gets the hate back, rather than let him cool off for a bit.