I would say that is perfectly in character for a combat soldier, to feel regret and guilt in killing another, regardless of the justness of the war.  Audie Murphy was tormented with it hsi entire life, after WW2 and Eugene Sledge writes of it in his memoir, With the Old Breed, which was included into the narrative of the mini-series, The Pacific (along with Robert Leckie's A Helmet For My Pillow and the story of Jon Basilone).  Both rightfully killed enemy soldiers, in a just war (Murphy fighting the Germans, in Italy and into Germany and Sledge on Pelilieu and especially, Okinawa).  Sledge dealt with an enemy that wouldn't surrender and training that taught him to kill them and even hate them; but he was still torn by those experiences.

Carol Danvers was an Air Force officer, though of an era where she would not have seen combat.  However, she had seen combat as Ms Marvel and Binary; and, now, Warbird.  She was steeped in the history and traditions of her training, as an officer (even if most of the writers who handled here were clueless about them) and would carry those lessons into combat, as a superhero.

While I agree that the idea of superheroes holding back, when there is no other option is ludicrous, I do not think it is wrong to show them wracked with guilt about having done so, even if it was the only option and was just.  I have no problem with Superman killing Zod to stop him; but, I do have a problem with the way it seemed o casually done, with no consequence in his head.  Don't get me started on the depiction of Jonathan Kent in that stupid film.  After Byrne did it, Superman starts to have problems, which fits within his character.  He had to stop the pocket universe Phantom Zone villains, but, he suffered guilt, which affected his actions, later.  That is fitting for one raised by Jonathan Kent.

It was excessive. By nature, Superman might have an issue with taking a life, but as with all things, circumstance allows people to place what is accidental, careless or what is justifiable into categories of acceptance or rejection. In the case of any media's depiction of Superman killing Zod, he was justified and should feel no guilt. A being of Zod's power blended with his intent (and the unimaginable levels of destruction delivered up to the point of the final battle) means there is no "safe" or "easy" way of stopping him. A villain of that kind--just as powerful as Superman--has nothing to fear and no one to listen to or respect. With that as his immoral guidepost, the only way to stop the seemingly unstoppable is to end Zod's life, knowing it was the only way, as Zod was no "lost" or wayward boy, he was not brainwahsed / under the influence of another being, or anything else. The Man of Steel movie handled this perfectly, as it presented a Superman who did not set out to kill (IOW, he was not on a Punisher-like crusade), but reasoning only reached one conclusion for being who threatened an entire civilization. Superman was visible frustrated with the action he had to take, but as part of the growth process, understood killing Zod was necessary.

Human beings, in the Western World, are taught that killing is wrong, a sin.  Then, you have to turn that off to fight in a war and do what needs to be done.  It was justifiable to kill Nazi soldiers, who were slaughtering thousands without shrugging.  It was justifiable to kill Japanese soldiers who were trying their best to kill you and were also enslaving and slaughtering people in conquered territories, as well as torturing and killing prisoners.  You kill and you move on.

When the fighting stops, you have time to recall what you had to do and it can weigh on you, especially as you face the fact you took a life, when everything before taught you that it was wrong.  That conflict is a tremendous battle of the mind and it has taken down many, who did their duty, in a just cause.

Superman was raised by the Kents to respect all life.  They were farmers, connected to the land and the animals.  They understood how life was interconnected.  When Clark's powers started manifesting, Jonathan could see how they could be both blessing and a curse, if Clark didn't have the right guidance to direct them.  Clark was capable of killing without a thought, by a reckless action.  Jonathan taught him to think about his actions and their consequences.  He had to make a deliberate choice to kill the Phantom Zone villains, to stop them and they, arguably deserved it.  But, to Superman, it was a failure of imagination that he could find no other solution than taking a life and he was haunted by that.  It was more than past action, though; once you have taken a life, the next life can come quite easily...and the next.  It wasn't just taking those three lives; what would Superman do the next time?  What if he took a life because it was quicker and easier than finding that alternative?  What if killing came more easily, each time?  Then what?  That is part of the guilt.  That was part of why he developed the split personality and why he removed himself from the planet.    he struggled with the necessity of his action and the ramifications and the potential outcome, next time.  When he became the faux Gangbuster, the side that said it was right was in control.  When he went into exile, in space, the moral side was in charge, telling him he had to be punished and apart, until he realized, once again, that heh ad a duty and a responsibility to use his powers to help others.  he finally made peace with what he had done and moved on.  The road to the destination is very different for each person who goes through it.  Some find that peace quickly, some never do.

I never experienced combat, but I have killed animals, while hunting and fishing.  We ate what we killed; we didn't collect trophies.  However, we were out hunting, on my grandfather's land and my father wounded a rabbit.  He picked it up and it started thrashing and squealing and he quickly bashed its head against a tree to finish it off and end its misery.  He took no pleasure in it; it was just what had to be done.  At that moment, though, that rabbit was no longer a target or food, to me; it was a living thing and it felt pain, even if my kill was quick.  I couldn't hunt anymore and put away my shotgun and never fired it again.  I still eat meat; but, I don't hunt or fish any longer.

My father also had to make a choice, later on.  The family dog was old, blind, deaf and in pain.  They were going to have him put down, by a vet and made an appointment.  My mother worked that day and was late getting home, and told my dad to hurry up and bring the dog and they would rush to the vet's office.  My dad told her not to worry about it.  My mom didn't understand and told him that they could still make it.  He told her it was done and never said another word about it.  My father had ended the dog's suffering and buried his remains.  He loved that dog and he loved animals.  He didn't kill them or torture them indiscriminately.  However, he grew up on a farm, in the Depression, on land that was hard to farm.  He hunted and fished to supplement their food.  He had killed chickens for supper.  He didn't grow up to be a farmer, though.  He became a teacher.  He didn't agonize over killing the animals he had, but that doesn't mean he didn't suffer guilt, over some of them.  I know he was torn about ending the dog's suffering, which was right, and killing a creature he loved.

Eugene Sledge wrote that the killing that he had to do and those he fought was a failure of Mankind, that they couldn't stop this cycle of insanity and lived, peacefully, together.  Superman is like that, he sees the good in mankind and does his best to stop the wicked; but, he sees it as a failure of their potential.  Hs battles against Lex Luthor, in each incarnation, boil down to the failure of Lex's potential, especially the Silver & Bronze Age Lex, who knew Superman, as a youth.  That Lex was poised to be one of the greatest mind's in human history, who could improve the quality of life fore the entire planet; yet, he was obsessed with killing Superman and criminal activities towards that goal.  Even billionaire Lex was squandering the resources he had, in a bid for power and adulation, rather than aiding mankind.  That failure of potential is what weighed on the modern Superman.  Each madman he stops, each criminal he scoops up is another failure of Mankind.

I never read it, but I was at a con where Fantagraphics presented a slide show that pushed Dalgoda as heavily as Love & Rockets

The most I read of Dalgoda was a short piece in the back of Doomsday Squad.

I just saw a pic of a slabbed 1.5 Avengers #2. Why bother ?

Like when people used to play with toys rather than leaving them "mint in box."