Correct me if I'm wrong, but he was on Earth to protect the Cosmic Egg, right?   Human but still with his powers.  The Serpent was wreaking havok all over the world and coming after the world tree, where Loki hid the egg.  So why was SS left out of that arc? 
 
BTW, that whole arc was lame.   Thor takes out the Serpent, who's supposedly Odin's equal, in two or three disjointed panels? C'mon....

From my estimation the events with the cosmic egg happened before fear itself and after dark reign, he became a member of a new defenders lineup with savage she hulk, namor, a mutant named Loa, and Dr. Strange who fought against attuma who got a hammer in a side story call "fear itself: the deep."

thor took on two worthy

sliver surfer & thor are very close in power level as seen in there fights so why couldnt the surfer have taken down one worthy by himself? thor did?

smh fear itself could have been better

Because he knew it was garbage and that Fraction would somehow manage to de-power or kill him.