Those instances are from the somewhat surreal Golden Age when many heroes were soulless Nazi killing machines. The cleansing combination of Comics Code conduct and Silver Age sensibilities did an effective job of keeping the violence in GA comics from having either a spiritual or literal impact on Bronze Age heroes. In more modern comics, the Golden Age violence has been referenced quite a bit. In some cases resulting in interesting stories, like Ed Brubaker's Captain America run. Others, like DC's failed First Wave line, not so much.
Still, in today's modern world of violent comics, you sort of have to wonder how we got here. Which heroes in the bronze age crossed the line first?
Normally, we associate this paradigm shift with Wolverine and Punisher, and rightfully so. (and possibly Deathlok to some degree.) But were they really the first heroes to mae killing in the Bronze Age acceptable? In those cases, they were seen as sort of antiheroes or rogue heroes whose exceptional behavior proved the rule. I believe nightly news era accounts of the Vietnam War have more to do with violence in comics than the Punisher's rubber bullets. Also, you can see this trend slowly creeping in if you look at other comics from the era. Here are a few examples.
In Avengers 117, during the classic Avengers/Defenders War, the Swordsman (albeit a hero who was once a villain) kills a man:
When I was a kid, this scene made quite an impact on me, and I have to wonder if it didn't play some small role in the Swordsman's death later on in the series (much in the same way that the Phoenix's burning of an entire planet caused Jim Shooter to demand she pay for the crime.)
Next is a death scene I dare you to have forgotten. The classic Cap/Baron Blood showdown from Captain America 257:
My final example is one a lot of people either haven't read or don't remember, and that's when Princess Projectra makes Nemesis Kid pay the ultimate price for killing her husband Karate Kid.
At the time, I felt she was totally justified in her actions, but looking at it today, I have to sort of quibble with her excuse that she has the she can take the law into her own hands because she was born into the right family. :\
Again, I think we can all agree that the real leaders in the bloody revolution in comics were Wolverine and the Punisher, but I believe these examples indicate other writers were picking up on the climate change as well.
If I missed a similar death scene from the era, please let me know.
Have a great weekend!