The Judeo/Christian system of heaven is very organised with different angels, class of angels, prophets, and today ministers, pastors, bishops, etc. They each have a role.
Jesus for example is placed in charge.
Seraphims guarding the gate of Eden.
Cherubs guarding the tablets.
Archangel Michael is in charge of the heavenly army.
Your question misses the point much in regard to actually placing God as God, rather than a personified character. For example, God created everything. What is everything? Everything must be part of God, for without God, you can't have anything created for all are part of "him". Science explains this also with dark matter and matter only taking up a very small portion of it all. Planck scale and supersymetry regarding connectivity of all things.
So, you look at Michael. Michael has El at the end of his name. El means God. We know this because God is called Eloh, translated in arabic as Allah. Michael then means that he is part of God or an aspect of God. So, God isn't really sending someone else, he is sending a personification of himself in the form of a very defined entity - Archangel Michael.
Here is some others... Gabriel, Rathael, Uriel.
Another interesting point is Israel - which as you probably guessed means his people or El's people or God's people.
Keep in mind that the bible has different canons and in different times the church will pull different canons to present to people based on the times. Currently the King James bible which is suited for a protestant world is presented.
Something was being presented here. God doesn't need to have a fight with anything as all things are "himself". Rather what I can see is that some things were being presented such as the fight of light and dark (sunset and sunrise from Egyptian mythology) and principles of chess (black and white players), and also the fight between Ahura Mazda (good mind) verses Angra Mainyu (bad mind).
It was the total misrepresentation of this last point that made man put a man or womans colour to signify good and bad rather than the virtue of each person. A very unfortunate thing for all of humanity, but I am glad we all a bit wiser today.