Some strange things drops in certain dungeons. Furthermore they are useful at times. One of those is Essence of Pure Jealousy, a QL 42 that drops in stacks of 3 of a mob called Jealousy in the Steps of Madness. Don't split this stack, you need to use all 3 charges in one go.
And the item you're applying it to? An Aggression Multiplier, found as mission reward, in chest and also sold in shops (to a certain QL). QL of Aggression Multiplier does matter, since it sets the QL of the final product.