Not only for someone cuz i would say for 2 people because when u nova'd someone if a second target get nova'd after you first frostbolt you have time to cast another one on the second target. Frost seems fun but less damage than cata frost.
Both are really nice imo, but yeah arcane for burst and frost for more cc. Still crit around 500 frostbolts unbuffed though I think, it's not that bad considering the amount of cc you got
I have a mage I might play frost. 3 bolts up 2 shatters on someone is nice. I do it in f2p alot but then again mages are much different in f2p. Arcane is shit and frost shines