I have an Ice/Ice dominator, which I like in PvP. Arctic Air and Ice Slick are just about maximum slowdown so I can keep just about everyone still while my team defeats them. You might not need that slow enhancement in Arctic Air. Also, I find frostbite fairly useless. I've yet to have a situation where using it would have saved anyone.
I don't know if there are any toggledroppers in /psi, but if there is, you might want to take one. Especially useful against tanks who have a damage aura like Mudpots. With all the slow there, they can't really hurt you and when you drop the aura, the stalkers can attack safely.