Arcane Knight Help

[Commiades]

I've just got a mage intended to be an Arcane Knight through the necessary quest. Mindful of a comment by P4ran0id that it's a high level build I didn't hurry this and am now level 16. I've tried it out with Arcane Blade and Combustion maxxed and then with these dropped a little so I could include Death Cloud and Vampiric Blade. Some questions:

1. What to do with Mage Armour. It seems to ablate too fast and become a mana drain to renew? Just have it at 1 for traps? It's great for a ranged mage and the elemental protection is helpful too, but I'm not finding it so good for an Arcane Knight.
2. How to handle shadows? Do you maintain some competence with a wand or staff?
3. How to handle enemies resistant to all elements (or only vulnerable to toxic damage)? Again do you use Acid Spitter?

 

[Arcanmaster]

How to handle shadows?

Thoughts​

The lowest resistance is cold +50
Maxed Combustion -60 resistance, costs 45 mana with 15 s cooldown (3 mana per second ≈ Arcane 3, anyway, taking train of shadows is bad idea so you won't combust crowds and you should kill weaker shadows faster then 15 seconds so practically it will be mana costier or you won't combust all mobs)
Blade of Deer has biggest ColdDPS for melee weapons (bigger then Primal Icicle and Queen's Heart)
I am dreaming about Mage with First Winter and Maxed Combustion clearing Forbidden Pit.