I get really tired of going round with first time watchers of Buffy who assume that simply because Anya used the words "If you want to defeat a God use the weapon of a God" that this somehow means that Olaf was a God.
Let's follow the argument from the stand point that Anya turned him into a Troll in the first place as her only act of vengeance BEFORE she accepted De'Hoffryn's Offer and became a Vengeance Demon. Some say that it was Aud/Anyanka that turned Olaf into a God but if you stop and consider that she was performing a spell that required ingrediants (eels bane) and she wasn't even a Vengeance Demon at the time of casting the spell so had very little power, it really doesnt scan that she was even capable of such a feet let alone inclined to get back at her "boy-friend" by turning him into a God.
Most of the tension around the final episode of season five has to do with the fact that Buffy has NEVER faced an advesary that is a God, (as pointed out by the Watchers Council) yet we know that Buffy has faced and defeated Olaf.
Anya herself indicates that Buffy needs to get the hammer out of Olaf's Grasp in order to defeat him, though she explains after the fact that he "still has all that Troll Strength!"
This then is the final proof that Olaf is NOT a God himself but merely carrying
"...the weapon of a God." Here ends my rant. Thanks to all who take the time and interest to read it.