There is a question in the traditional occult world on where Michael resides. It normally comes down to two possible choices; Michael is either solar or mercurial.
Now I have always had him over mercury, but I took a deeper look into this particular question because of such a trend I started noticing lately. So I made out a list for both expressing the qualities that are fitting to Michael set over the Sun, and another one set over Mercury. When I was done, it still seemed to make more sense to have him corresponding to the sphere of mercury. Here are my notes:
1. According to Pseudo-Dionysius in his book, The Celestial Hierarchies, there are nine major angelic orders divided into three sets. These are in descending order Seraphim, Cherubim, Thrones, Dominions, Virtues, Powers, Principalities, Archangels, and Angels. The last triad(Principalities, Archangels, and Angels) are the only group of angelic entities that directly interact with the general populous with the exception of initiated mystics and magicians. If we were to label each order with the spheres in an ascending order we would get Angels set over the Lunar sphere, Archangels over the Mercury sphere, and Principalities set over the sphere of Venus. We know that the regular people who attend religious services often ask Michael to intervene on their behalf, but if Michael was set over the Sun then he would not be in the triad of angelic orders that regularly intervenes on behalf of the common populous(Principalities, Archangels, Angels).
2. If we look now to the common practice of those who honor Michael we can also see mercurial elements. Already stated above, Michael is venerated as a divine messenger lifting the prayers of the people to the heavens. This sounds a lot like Hermes and Mercury of the Greco-Roman pagans. He also carries the soul of the dead to their place of everlasting, which traveling naturally corresponds nicely under the attributes of mercury. Some may point to his images with the scales and say that judging the dead isn't a mercurial attribute but a jovial one. I would agree. But according to the doctrine of Christianity it is Jesus who Judges the quick and the Dead and not Michael. Michael holds the scales to show that he is involved in the scoring and measuring process much like Thoth would have been in the hall of Maat. Some may also speak of Michael as a soldier stating that he is even Martial rather than Mercurial. I would say that they don't understand the role of mercury in classical astrology; he is changeable by his nature and thus receives the nature of the other planets. He is beneficent with some planets and destructive with others. But either way, Mars is not even a question here. It is between Sun and Mercury where the confusion lies. The multiple roles Michael plays also helps to once again demonstrates his ability to change from one to the other which of course is another attribute of Mercury.