If you stay s/s, stay INT for sure, as people already said. You're phy defence will go up if you up your ice mastery to 80, and even if you let ice be 60 or whatsoever, mana-shield will give you a 120 sec (2 mins) 'def boost'. If it can be called that way

At Lv60 it'll take 40% of the damage away to your MP for 2 minutes straight. Or untill ur out of mp pots
Pure is always the way to go, for STR
and INT. Not saying hybrid sux.. (I'm hybrid too >.>) But only go hybrid when you know what you are doing.
Don't fck up (: gl