I also think that the passive bonus of Geomancy is quite weird because main damage of this mastery is earth damage. Besides, I can only remember 2 skills restoring physical armour at the moment.
The poison might still do more damage with the Overtime factor. It would seem the earth damage are usually spells with secondary effect (Slow, cripple) and aren't fully about damages. But only in the main game we will be able to see that.
You actually have 3 skills:
-Geomancer's Fortify
-Polymorth's Heart of steel.
-Generic shield skill is also affected by it.
I made a melee combattant with 9(+2 from gear) Geomancer, 1 Warfare, 1 Polymorth.
And even with a crappy 266 physical armour (from the Tyrant set and a decent shield) with both buff he has 535 armor and regens 56 each turn. All of that with a one handed that has a base of 12-13 poison damage (*1.9 thanks to 9 geomancer) he still deals pretty good damage, is hard to takedown and helps wearing down magic armour for mages in the party.
