It turns blue.

The action hero in the exclusive company of men - proving himself only to his peers and eschewing the acts of weakness necessary to appeal to soft, emotional women - was held up in various forms as the epitomy of manliness in the environment of the 1980s action film to the extent that there are no women in Rambo 3 to soften his brutality and force him to display emotion, but that's okay because it is ultimately a film about the consequences of violence as the language of men.

Removed from the company of women, man creates his own alien landscape hewn from and sustained by acts of terror and savagery: the Soviet army use violence to hold Afghanistan and the consequence is a rebel movement, the rebels use violence and the consequence is retaliation against their families by the Soviets and so it goes in bloody red circles until the violence is escalated towards an end through the outside agency of John Rambo, who from the very start is shown as using violence merely as a means, stick fighting for money but showing mercy to a downed opponent even when that opponent doesn't extend the same courtesy.  Across the course of the film (and its two prequels) Rambo understands the cyclical nature of hostility, and because he and by extension the film understands this, violence is shown to render all participants - even its perpetrators - as victims, from the desensitised and dehumanised Soviets far removed from their own society to do what that society has deemed necessary - but unpalatable - to the brutalised Afghans who accept the rape and murder of their families as their lot, violence is portrayed as a self-perpetuating way of life of the male warrior class until forced towards an ultimate end.
Rambo tips the conflict in this direction by making the matter a personal war between himself and the cruel Soviet commander, but despite his being our POV character, there is little distinction between Rambo and the Soviets, and if anything his campaign is more brutal and terrifying than theirs, as in running headlong towards the enemy, he eschews the idea of an ongoing campaign of war between two factions in his pursuit of a quantifiable endgame he moves towards via the most direct route.  Along the way, the consequences of violence are graphically shown - especially in the infamous "cauterizing" scene - to the extent that for most people the one scene in the film that breaks it is the confrontation between helicopter and tank that signals the end of the third act, as one of the participants is seen to walk away from it "victorious" rather than be consumed and destroyed by it as would seem to be the inevitable result based on all that has gone before, with even that character's only friend in the world looking disappointed that he didn't die in the two warriors' inescapable and literal head-on collision - until this point, Rambo 3 is an unflinching indictment of violence, but even in betraying its central conceit it serves to better illustrate it, as by getting to walk away from the conflict, Rambo the character perpetuates the cycle in perpetuating the alpha male franchise.  The film unambiguously relays that Rambo will find no rest among civilised men, that at best he can hope only to live on the edges of society among those who recognise his capacity for violence and on occasion allow him to indulge it as a momentary emotional and physical release and expression of who and what he is before he returns to being haunted by who and what he isn't.  Rambo, like any extreme example of the action hero, is an eternal mid life crisis, taught the value of "victory" but ultimately only wanting something he cannot simply go out and take.
Thus I posit that Rambo 3 is morally superior to Man of Steel and is a better film for younger viewers to watch because in Man of Steel, violence has no consequence, and I don't just mean that Superman and the evil Kryptonions punch each other over and over and over again without any repercussions for minutes longer than necessary or interesting, I also mean that the end of the film glosses over the deaths of millions and the economic impact of the destruction of a major American city while Rambo 3 shows that getting punched will possibly kill you - Man of Steel couldn't even get across that two people of similar strength punching each other will at the very least result in one of them getting a bruise.  Rambo 3 has people getting shot and they explode in red fountains - or sometimes in literal explosions and a rain of body parts and organs - while Man of Steel has a rubber mannequin bounce around a bit when someone is hit by the fist-sized equivalent of a bullet train.  Rambo 3 has the F-word and gore, but these are shown as being bad and not admirable accoutrements of the rollercoaster 3D CGI setpieces and in the world of Rambo 3 - single-minded in its pursuit of the action spectacle as it is - death is final, terrible, and devoid of dignity.
There is, however, thematic overlap with Rambo 3 and Man of Steel in that they both portray the conflicting desires of a son and those of his surrogate father, but Man of Steel fails to suggest why one point of view or the other may win out in the end, as it is not about a man who discards the nihilistic and xenophobic "me me me" lessons of his Republican middle-American upbringing and becomes his own formed and rational person, it is instead about a man who is told to do one thing and does it until he is told to do another thing, and at all times is uncomfortable doing either.  There's no choice to the role he fulfills, no commentary on his place in a larger mechanism of society or even the idea of predestination, it's just one man doing what he's told and never showing any spine.  Rambo 3, by contrast, is about a man who understands what he is and lives in a constant state of frustration because of it, but when he acts, it is with confidence and because he feels a palpable human connection to another person that even the audience is aware of, not because he has been instructed to do so by a surrogate father - at one point he outright refuses to act in this father's name or interests because Rambo is his own man, but he will act out of love for another.  Even coming from a frightening, mentally unstable figure like John Rambo, this is a moral compunction I can understand, and further it is held by someone whose actions do not leave him unaffected.  In accepting his role in things from the off and the consequences of his actions, Rambo, unlike Man of Steel's Superman, is operating within the same moral universe as the rest of us, and thus no matter how many people he reduces to a red smear with a machine gun, he is still one of us, capable of the love and sense of community necessary of a cinematic hero.