I agree that I think Jane's Thor power and form came from Mjolnir/The Mother Storm.
I know, I'm just talking in the context of Aaron's run individually.
I'm not sure if the former two events are as much a sign of him being ineffectual as dealing with divine problems with no easy answer. It doesn't make him a bad or ineffective ruler if things happen beyond his control, and the Surtur thing was him actually trying to exer back control.
The latter was just a sign of the bad writing I think Odin has been saddled with under Aaron.
I mean, I personally like Thor with all his body parts, but to each their own
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Although I feel like Aaron is trying to make them more permanent then they should be in my opinion.