I ran some poison work claws (lol) in pvp for fun but it takes forever to build up effects. Even using dual poison whips (the one that's already poison) it feels so flow. Similarly using bleed claws. Maybe everyone is just stacking the shit out of resists.
I'm yet to be in a situation where bleed/poison does more than physical/elemental. Maybe against bosses but I'm not sure how it works against bosses.
Vigor is only for pvp, you don't need it for pve. For pve just stack whatever will make you deal the most damage.
I wouldn't recommend stacking dex just for poison since it only increases the rate you apply. If you are using cestus go 40/40 str/dex then 50/50 str/dex and after that maybe work on adaptability, endurance, etc, then push up past the soft caps.
Honestly stats don't matter for pve other than: being able to equip and carry your items/spells, and dealing MORE DAMAGE.
The other day I cleared up to and including iron keep with a pure adaptability deprived. I'm 2 handing a raw club and wearing tseldora. I only hit 300's against the mobs around there, so really it doesn't matter what stats, go pure attunement and it may take a bit longer to kill bosses, but you can definitel do it.