Poisoned Weapons and Etherealness ???

[Cohen]

In 3 of my games, it happened that Tritons killed my GK with ease, often if the 1st round of combat, swarming him.

Once however my GK had over 70 hit points due to high dominion ... but he was killed too in the 1st round of combat.

I'm thinking a poisoned weapon ignores Etherealness just as a magic weapon. It is right?
My GK wasn't poisoned since it's Poison Immune 100%.

Another question about poisoning ...
Does Manikin/Mandragora attacks are poisonous?
I managed to lose 2 Arch Devils sending them in battle against a CW Pangea army. They were both equipped with Snake Ring, but soon they got 100-200 fatigue and got slaughtered.
I believed that the Snake Ring would keep them safe from that ...