Use enchanter instead of Cleric. You get spec'd into Aero and Hydro, and you can even put 2 points into Geo for Physical Armour restro spells.
As for people who are saying stick to 1 type (like physical or magical), don't listen. Almost all enemies (including most bosses) will either have less Magical armour or less Physical. There are multiple enemies, mages can easily focus down the people with less magic armour and vice versa.
I'm playing with a friend, we're into late game playing on classic and have had zero trouble. I'm playing Wizard with Geo/Pyro. I got Sebille as Shadowblade, Friend is playing Fighter (warfare, poly) and got a enchanter with Geo as well. It's all about positioning and learning the tactics and what you can also do.
