Frost does everything, get hit on gloves and 3/3 precision (frost talent) theres your hit cap, Arcane is a gimmick, fire's ok but frost is a far better all arounder. 900 Fbolt crits with 500 CoC, near enough on demand 1.4k burst with nova up or frostbite proc, and thats not taking offensive cold snaps into consideration.
And your a caster, F AGM, get Tidal.
Also why would you make a class that you just want to CC with? what BS use is that lol... Why would anyone want to play with you if all you can do is throw sheeps around and a few R1 frostbolts? Good mages can throw out good CC and burst when needed, get out of this 'i just wanna cc' mindset and you'll be fine. Not to mention you'll have allot more fun.
As for gear. engi helm, eagle/boa shoulders, staff of Jord, I went with Robe of Magi - Rest is ok.
Just to reiterate. At 39, you dont need imp CS, baseline CS is perfectly fine, the burst is so quick a random imp CS or POM xx just isnt required, offensive blinks, tidals, sheeps, r1 frostbolts, you have it all with frost, the only difference between frost and lolarcane is that you have far stronger burst and defensive capabilities. Arcane is just pathetic at this lvl if you want to play with/against people with half functioning brains. If you are intending to play with bads all day every day, then ANY spec in the game will be fine for you. Hope this text burst helped.