Oh boy.
There are two Acid/Poison Dervishes I’d recommend:
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Dmt’s DOOMBABY - DOOMBABY - DW Dervish, superboss killer (c+)(SR+)(g3)
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grey-maybe’s Edgyswingsetacid - [1.1.7.1] Edgyswingsetacid - DW Righteous fervor Dervish [SR 90] [5.20 crucible] [Avatar, Ravager]
(God, these names 
)
grey’s is much newer (built for current patch) but also has a far higher item requirement. I’d start with shooting for Dmt’s setup and, from there, working toward grey’s if you want to push things even further.
As to specific parts of your build:
- You don’t gain much of anything by investing more than one point into Guardians of Empyrion.
- You do get some good damage from maxing Nidalla’s Hidden Hand, but you’d get even more by improving the proc chances and potential of your various weapon pool skills (WPS). Most agree - getting your Nightblade WPS to 19-20% (4-5 points in each) proc chance is a paramount priority. Getting more still into Execution is usually worthwhile too.
- You can take Smite to further reduce the chances you will use a simple basic attack.
- Unless you can hit 24/16 investment in Righteous Fervor, there is no real reason to go above 16/16.
- More points in Ascension is all but a must, defensively.
And finally, stay away from Requnix builds. In addition to being uniformly old and outdated, even when they were written they weren’t especially good or, at times, even sensible.