well To alot of us if you READ the phrase on the Side of Mjolnir it says,
"WHOSOEVER HOLDS THIS HAMMER, IF HE BE WORTHY, SHALL POSSSESS THE POWER OF THOR."
NOWHERE does it say the possess power of Mjolnir.
This has been an argument going for a LONG time. I guess it also depends on WHICH Thor you're talking about.
Say it's someone who IS worthy like Erik Masterson, HE was using Thor's powers THROUGH Mjolnir as Thor, but, it IS written that Thor was born with the weather control in Blood Oath.
Warriors Three had said that they had to hit Thor to wake him up from a bad Dream that was causing Storms when Thor was young.
There's also times Thor couldn't USE Mjolnir, Blood Oath being one of those times, and still had shown he controlled storms. The Ragnarok arc was another time. Mjolnir had been Broken and Thor still had his powers.
The MOVIE version seems to show that the powers come from not just Mjolnir, but, from his armor as well like Ultimate Thor, but even THERE it's been revealed Thor had powers before he came to Earth and had to depend on earth made equipment.
When Thor becomes unworthy of Mjolnir say the initial Banishment, he was stripped of his powers to teach him humility, to teach him there are other ways to solve problems with the use of violence.
In the Reigning Arcs Thor had become unworthy of Mjolnir because he Killed someone who had been worthy. He still had powers.
Mjolnir is a TOOL to focus Thor's powers. Yes there are SOME powers/Enchantments IN Mjolnir but not the weather control or Thor's Godforce. ALL Asgardians have a godforce, nothing changes that.
Thor's power/godforce is different from normal Asgardians as well because he's also the son of the Elder Goddess Gaea/Jord.
Thor's entire essence was inside Mjolnir. Under the 60 second rule, Thor had none of his powers unless he remained in contact with Mjolnir. In other words, ALL of Thor's powers were confined to Mjolnir and the worthiness enchantment.
In Thor annual #11 it was stated that Mjolnir's powers included weather control, granted by Odin. Thor was not naturally able to control weather according to that manual. Different writers have used different methods though. The 2007 "script" for the Thor movie shared this similarity. The hammer controlled weather.
Now, it seems writers adjust on the fly and there is no set definition on how much is Thor, how much is Odin, how much is Gaia and what his actual Birthright is. No continuity at all.