Hanson doesn't get much into philosophy, but I wonder how much the philosophical distinction between nature and convention that I mentioned in this post has contributed to the lethality of the West. Cultures that do not possess this philosophical distinction (and it seems that they do not prior to their encounter with the West, but I am not enough of a cultural anthropologist to say this categorically) tend to have a conventional way of fighting. By this I mean a way of fighting that is not necessarily rationally ordered to the end of victory, but is a stylized way of fighting that has developed for peculiar religious or traditional reasons.
For instance, the life of the Crow warrior was centered around "counting coups", which meant performing bold exploits against the enemy. Lear writes that
If the survival of the Crow tribe as a social unit had been the primary good, one might expect that highest honor would go to the warrior who killed the first enemy in battle, or the warrior who killed the most. But to count coup it was crucial that, at least for a moment, one avoided killing the enemy. There is a certain symbolic excess in counting coups. One needed not only to destroy the enemy; it was crucial that the enemy recognize that he was about to be destroyed.
Lear analyzes the notion of counting coups and concludes that, for a nomadic hunting tribe like the Crow, the crucial point was to establish boundaries with respect to other tribes. The form that counting coups takes with the Crow makes sense from this point of view; tapping the enemy with your coup stick before killing him makes him recognize the boundary he has violated before he dies; taking his weapons from him while he is still alive demonstrates that he cannot pass this boundary as a warrior:
The establishment of boundaries will, of course, be important to any cultural group. But it is especially tricky when it comes to a nomadic group whose migration depends heavily on hunting. As the tribe migrates, its defensible boundaries will shift, but it needs to be able to exert a proprietary claim over the animals within its (shifting) domain; and it needs to be able to repulse the proprietary claims of its rivals. Counting coups is the minimal act that forces recognition from the other side. The about-to-die Sioux warrior is, after all, about to die: if all goes as planned, he will be no further threat to the Crow. Recognition of the Crow boundary is the second-to-the-last thing the Crow warrior wants from him. (The last thing is his scalp, but that will serve as a token that he achieved that recognition.) If the tribe's goal is the firm establishment of a boundary, then the act of counting coups is not excessive. It strikes the mean between the defect of wishful thinking that one has boundaries when one is unwilling or unable to defend them and the excess of slaughtering one's enemies so quickly that one does not obtain from them recognition of anything. When struck with a coup-stick, the Sioux warrior recognizes a Crow boundary because he also recognizes that he is about to die.
The problem with Lear's argument is that, since the Sioux warrior is about to die, what does it matter whether he recognizes a boundary or not? If the establishment of boundaries is the goal of counting coups, then what matters is whether the surviving Sioux recognize the boundary, not the dead Sioux. Furthermore, even if Lear were successful in establishing a rational goal for counting coups, it doesn't follow that the Crow counted coups for those rational reasons. Lear's analysis attempts to show that the conventional form of Crow courage is the form it should take according to the nature of Crow life; in other words, it is an analysis from means to end. But there is no reason to think that Crow traditions were established with this sort of rational analysis. They seem to have developed innocently and unreflectively, like most traditions within aboriginal peoples.
Counting coups is reminiscent of the Aztec way of war that Hanson discusses in Carnage and Culture. Aztec weapons were not particularly lethal; their purpose was to stun the enemy so the Aztec warrior could drag his opponent back to the pyramid to be a ritual human sacrifice. It turns out that this way of fighting was effective against other native tribes for psychological reasons. But it is unlikely that it developed as a deliberate way to psychologically demoralize the enemy. Probably the religious ritual came first, and it was later discovered that Aztec warriors capturing the enemy to be human sacrifices had a particularly devastating effect on their morale. Whatever the case, it didn't have much impact on the morale of Hernan Cortez and his men. One reason so few Conquistadors were able to conquer an Aztec empire of hundreds of thousands is that the Aztec way of war was singularly ineffective against Spanish steel. But, more significantly, the Aztec could not adapt their methods of war to the novel enemy constituted by the Spanish. Their staggering losses to Spanish swords and armor did not cause them to reconsider the practice of human sacrifice as a way of war. Courage for an Aztec warrior still meant dragging an enemy off to the pyramid. They had no rational tradition of philosophy to treat warfare abstractly as a mean to an end, or to understand courage as involving means to an end.
Although Cortez was not a philosopher, he was raised in a culture that was informed by the philosophical notions of nature vs. convention and means vs. ends. Courage in the West is not finally specified by a particular act in battle, like striking the enemy with your coup stick or stunning him so he can be a human sacrifice. It means overcoming your fears and facing lethal dangers in the service of victory - whatever form that might take in any particular situation. Cortez approached the Aztecs rationally as a military problem to be solved. (The moral analysis of the Conquistadors is another subject entirely.) He even went so far as to construct his own navy from scratch to eliminate the Aztec mobility on the lake surrounding Tenochtitlan.
It is the Western tradition of philosophically-based rationality that has made it so lethal, for it has given the West a flexibility and creativity in war not known to non-Western peoples.