Sauron's 2nd and 3rd age power
 

I am puzzled by sauron's capabilities between the 2nd and 3rd ages. At the end of the 3rd age he is ringless, yet if the free people of middle earth attempt to assail him with war they would be swept away. Yet when he has the ring in the 2nd age, he is forced to used deceit to destroy numenor, and cannot withstand the remaints of numenor and the armies of gil - galhad. Do these events pay homage to the sheer power of the enemy's of sauron in the second age, and does it point to restrictions in the rings power ?

I think the answer is that indeed the enemies of Sauron were far, far more powerful in the terms of military force in the Second Age.

The general process in Middle-Earth is declining, not ascending, that is, everything is better at the beginning than in the end, and with time, it fades. The kings of Noldor in the First Age were mighty, and Gil-Galad was only a poor reflection of them. Yet still, in comparison to the Elven kingdoms in the Third Age, he was a mighty king worthy of many songs. Similarly, the Númenoreans had a great realm which at its height ruled a large part of Middle-Earth and even countries "outside the map" far to the South, but Gondor and Arnor were "the realms in exile", where also the Númenorean population was not that strong and many of the "citizens" were "lesser people" originally from Middle-Earth.

At the end of the Second Age, it was the military power of united Elves, Men and also some (few) Dwarves which defeated Sauron. In the Third Age, there were no hopes for such a powerful reunion anymore.

Yet again, fitting for Middle-Earth, it could not have been the sheer power which would bring the ultimate victory.

I think this is right. In the first age, the Noldor took on Morgoth himself, and Sauron was only a lieutenant. In the Second Age, the Numenoreans were in some fashion blessed by the Valar for their resistance to Morgoth in the First Age, so they evolved their own nearly magical kingdom. In this respect, they were imbued with power from the Valar perhaps similar in fashion and scale to what Sauron was capable of in making the Rings of Power. To me this is perhaps more significant than the power held by Gil-Galad, even if that was substantial. In the Third Age, the blessing and support of the Valar for men and Middle Earth has been largely withdrawn, with the exception of their sending the Istari to counter Sauron.