When I try to think of what enhancement's most iconic ability is, a few come to mind. Windfury Weapon is a definite contender, and three or four years ago it would have been my default response. Seriously, though, what is Windfury other than a glorified auto-attack with an attack power bonus and a lower chance to miss? Likewise, Stormstrike could be iconic, but it's essentially a melee attack with both weapons with an electric graphic and a debuff. It's enhancement's Mutilate or Obliterate.
To me, Maelstrom Weapon is the answer. If there's one ability that encapsulates what enhancement is -- a brutal melee class that weaves instant spellcasts between their weapon strikes to harm their opponent or heal themselves -- I believe it's Maelstrom Weapon. It's enhancement's Death Strike, Arcane Blast, Chakra, or Raging Blow -- abilities that, at a glance, offer an insight into what makes the spec different from other specs in their role.
There's a problem here, though. If Maelstrom Weapon is enhancement's iconic ability, why is it currently so awful?
The problem with Maelstrom Weapon
There once was a time when firing off a Lightning Bolt at five stacks of Maelstrom Weapon was the highest priority ability we had. (This time period was Wrath of the Lich King, and this is the only time you'll ever hear me talking about it nostalgically.) It was our highest priority for a number of reasons, but it basically came down to this: It was high enough damage that wasting even a single potential MSW proc by holding on to stacks was a grave error. Reacting to MSW procs was part of the fun of the spec.
There's a problem here in that we aren't incentivized to hit five stacks. Hitting five stacks just means that we'll have to delay the spellcast anyway as our more powerful abilities come off cooldown, while casting early means we won't waste potential procs and won't be sitting at high stacks for long. And, it's more DPS to hard cast between cooldowns, so why would we ever wait until five stacks?
How to make five-stacking worth it
At its core, Maelstrom Weapon is an interesting ability, and its main issues come from how clunky and inelegant it has become to use. For healing, Blizzard has implemented an awesome glyph on the beta that helps to deal with Maelstrom Weapon's deficiencies, called Glyph of Healing Storm. It encourages the shaman to try and wait for that last charge of MSW to get a 100% bonus on that next heal. I managed to crit myself for 140k on beta last week (40k of it was an Echo of the Elements proc), and it was the first time in a while where I was truly thankful for Maelstrom Weapon's existence, even though 100k of it was overheal at the time.
This problem has been solved already
Instead of just looking forward, we can look backwards for solutions. When hardcasting started being an issue in Wrath of the Lich King, it just so happened that the four-piece set bonus on our Frost Witch's Battlegear gave us a 15% chance to increase our attack power by 20% for 10 seconds when our Maelstrom Weapon hit five stacks. For an entire tier, we didn't hard cast Lightning Bolts, because blowing a MSW early meant losing a chance for an attack power buff.
Failing that, I'd like to see Elemental Blast's cast time increased to 3 seconds (with damage increased proportionally) and see its cooldown removed. This would result in higher damage MSW casts and provide a buff to us for getting those spellcasts off, and the longer base cast time should serve to make hard casting impractical. The downside, of course, is that this would make the spell next to useless for restoration and impractical for elemental. But restoration doesn't really need a damaging spell that doesn't return mana, and elemental is effectively chained to choosing Unleashed Fury anyway, so I'm not sure they'd mind. We'd also be forced to use Elemental Blast as our top tier talent, too, but it's currently the most attractive one anyway, provided it works with Maelstrom Weapon like we all assume.
Show your totemic mastery by reading Totem Talk: Enhancement every week. We've got enhancement-specific advice on 4 ways to increase your DPS, the ups and downs of enhancement in Dragon Soul, and gearing up for Raid Finder raids.