I've searched and searched, and while I found answers, some were conflicting. Was wondering if anyone actually had a definite answer based on full and certain tests. Currently the various answers I've found indicate probably 1 of the following:
1. Direct increase to your damage, so if you do 100 DPS and equip a +6% to poison damage item, you will do 106 DPS.
2. Increase only works on physical damage and doesn't apply to elemental damage that comes from your weapon affix.
3. It's bugged as hell, god knows.
And of course each of those options might be display-only with the actual damage being something else...
Zunimassa's chest+boots combo (with high vit/int rolls on chest and some high all res and/or int/vit roll on boots) seems very promising for cost effectiveness, but only if the poison damage really gives the full 5-6%. If it adds ~1/2 of that (due to weapon elemental damage from weapon not being affected) then it might be still cost effective but not so obviously. If it doesn't work at all then it's really not all that impressive.
Any (conclusive) ideas?