How this works in practice we have no way of knowing, but there is much we do not know about how things “work” in the spiritual realm.
2 Kings 19:35 says, “And that night the angel of the Lord went out and struck down 185,000 in the camp of the Assyrians. And when people arose early in the morning, behold, these were all dead bodies”
Yes, we can see the results, but we are not told the particulars of the weapons used.