It seems it would have been mostly 'taking the fuel out of the tank and putting in some different fuel' so to speak

Which i find a tad dissappoint, to me it in ShB it sounded more like Zodiark was so powerful he would've been able to alter reality to just reconstitute the souls themselves from aether or something.

Honestly I found some of the elaborations disappointing on him, like it sounds like he just put a curtain of aether over the planet as a shield then 'altered the laws of the star' as they described it.