For a dual wield Nightblade with low button use I would suggest a pierce Blademaster (ie Soldier as secondary). You will have Cadence as a default attack replacer than you can put on left click and which will trigger the weapon pool skills in the top row of the Nightblade tree (and Soldier’s own WPS). Also lots of strong passive support skills.
Here is a quite old guide for a standard-issue Pierce Blademaster:
Here is a much more recent guide for a similarish build that leans into the Ring of Steel skill. Extremely strong build.
An Acid/Poison Dervish (ie Oathkeeper) is another possibility. Again, you will have a default attack replacer (Righteous Fervor), good supporting skills. Lots of target-farmable green gear that you can get.
For a cold dual wield build, the new Berserker would be the simplest choice as it has a DAR and great cold support.
Devouring Swarm needs to be cast every few seconds. It’s really used for -vitaliity and bleed RR and isn’t a natural fit for a dual wield Nightblade unless you are using those damage types, which is possible but which needs specific gear.
The Shaman’s panther, aka Primal Spirit, is a pet skill that needs pet-focused gear to shine. It’s also not a natural fit for a dual wield Nightblade.
Btw, it’s rather key to decide what damage type you want to run. That makes the decision much simpler.
[ Edit: remembered existence of the class I am actually playing. Jeez. ]