I'd hardly call it their best skill, but it's definitely not their worst.
For it's MP cost and mediocre damage in comparison... it's pretty bad IMO.
The 4 or 5 second blinded screen/banish effect hardly makes up for the more than four times more MP it costs and less damage than Celestial Strike. Though that's how I feel about it in PvM/Bossing.
In PvP I suppose it's good, if you can hit with it and not take half of the other players on the map as well by accident lol.