I'd be careful with Carl Schmitt. Even if I accept some of his arguments, his mindset was essentially an authoritarian one.
Yes I'm aware of much of the controversy around Carl Schmitt. Nevertheless he has been influential in modern political theortical discourse. I don't always agree with him, but he often gives powerful critiques of common liberal assumptions.
The fact that the service is voluntary, makes it much more heroic in my eyes.
Not really, it's not very noble to make a career out of killing. Niccolo Machiavelli outlined the dangers professional soldiers pose to any republic, due to the fact that without a war such soldiers are without a means of living. As he put it: "War creates thieves, and peace hangs them."