I have a Blog Post about Saint Seiya regarding atomization.
https://vsbattles.fandom.com/wiki/U...der/Saint_Seiya_-_Destroying_Atoms_Since_1986
Atomic Destruction is a concept from Saint Seiya that has been present from
Chapter 1 of the Original Manga. It has been repeatedly stated and explained in detail countless times throughout the franchise, present in almost every installment.
Classic, Episode G, Lost Canvas, Omega, Saintia Sho and I'm almost sure Soul of Gold, Next Dimension and Episode G: Assassin have their mentions as well.
Why do the Saints not one-hit-kill each other, them? Simple. Much like Cosmos's offensive characteristic is to destroy atoms, it's defensive characteristic is to endure atomic destruction.
If you want examples: Here's Leo Aiolia punching Photon Particles when moving Faster than Light.
http://imgur.com/a/3ujL6
Here's another (In PT-BR), Leo Aolia re-attaching a sliced limb through Cosmos manipulation.
http://i.picpar.com/NXKb.jpg
Translation of the First 7 panels:
"You can become whole."
"You can bun burn your Cosmos and finish your enemy."
"How is it possible if my heart is destroyed ...? I shouldn't even be capable of moving"
"That is because they are yet to be truly destroyed."
"Remember what you mentioned about this man... About his power? That he could undo and separate the connections of every substance."
"Neither your heart, nor your right arm are yet lost. Your fangs have yet to be broken. As humans, we possess the power of the intention of transforming things, and that is what atoms do."
"May your Cosmos burn! With it, make it so that the atoms unite! With your own Cosmos you shall recover your fangs."
And here is he actually doing it:
http://i.picpar.com/OXKb.jpg
Translation: "His heart and right arm, which have been destroyed at an atomic level... Were regenerated and united through his Cosmos."
I make my case, Atomic Destruction in Saint Seiya is an actual thing and they don't one shot each other because they have endurance to it.