Offers very high damage at cost of low survivability and low sustainability.
Arcane and Frost are perplexing and problematic respectively.
(Generally) Weak damage but offers high sustainability + survivability.
This spec is infamously bizarre and I can see why it confounds people to this day.
It seems to be intended as the 'PVP' spec (like Arms is for Warrior or Ret is for Paladin).
It's supposed to offer good 'sustainability':
BUT ironically its two 'capstone/core' abilities are each on a 3 minute cooldown
SO Arcane is actually infamous for having terrible sustainability due to only being 'optimal/powerful' once every 3 minutes.
AND PVPers generally dont concern themselves with 'sustainability' anyway as resurrection is assured (and restores all HP/Mana).
It's supposed to offer good 'survivability'
BUT ironically 'Arcane Missiles' are AWFUL in PVP due to not being burst damage and being easily interruptible due to channeling time. If you can't swiftly kill people (or at least scare them away) you will be dying very often/quickly.
and 'Arcane Explosion' can only be (optimally) used while literally surrounded by enemies... who are naturally going to be killing you within seconds.
Weak damage but offers high survivability + crowd control & AOE.
This spec is supposed to have inferior damage as 'payment' for all the control and survivability
But ironically it gets 100% bonus damage from Frost Spells so it actually generally hits much harder than Arcane.
Yet its survivability is infamous. They are often literally unkillable (Ice Block(s).
Its AOE ability is also overpowered -- easily mopping up huge groups of enemies.
Its control is unmatched -- Freezing/Rooting/Slowing and such.
TL;DR:
Arcane is supposed to be 'the PVP spec' but is in reality merely a mediocre meme in PVP.
They should be made to be less reliant on the PoM/Pyroblast gimmick to be successful in PVP.
Frost Mage is overpowered in PVP (and PVE) so their 'bonus damage' should be nerfed from 100% -->50%.
Either that or nerf various other tools they have such as Ice Block.