It was a bolt of lightening from the
God of fucking Thunder.

And this was
after Thor had punched Iron Man through several buildings. By Thor's own admission he was, "No longer holding back" in this fight. Bear in mind that Thor can summon lightening bolts powerful enough to kill the Sentry, who is the living avatar of the Wrath of God.
There's a huge difference between one of the most powerful beings in the Marvel Universe, especially when he's pissed off enough to bring his A Game, and a human being. No matter how smart, talented and dangerous he is. At the end of the fight, Thor warns Tony not to attack Asgard or, "Learn again the difference between a God...and a man in a metal suit."
Iron Man fucks up Batman even worse than Bane did.:icon_twis