The truly sharp weapons in the setting are the bladed power weapons that couple the monomolecular edge with a power field that disrupts the molecular bonds of the target to make it easier to cut. Absurdly Sharp Blade: While the basic close combat weapons of the more technologically advanced races would be some of the sharpest weapons in many settings, due to having monomolecular edges, such blades are no better than a basic iron bar in the game itself.On the other hand, the Tau are running an Orwellian society that makes it clear that they're staying the top ( depending on who you listen to), they have practiced extermination on species that are incompatible with the Greater Good, and finally they can afford to be so optimistic with other species because they've encountered relatively little in the way of treacherous or particularly offensive species besides the Orks and Tyranids who in respective order lack the concept of peace being a rogue species of living weapons and lack any instinct other than hunger. To be fair, they seem to be running a successful society built around a coalition of species. The only hard exception to this trope is the Tau Empire.On the other hand, it's not always strictly adhered to: being an absolute xenophobe eliminates any hope of alliance with the remaining 10%, which is why the policy of "Kill the Alien" gets tossed out when an Enemy Mine situation happens. This is possibly justified in that 9 times out of 10 any alien in the known universe will kill a human on sight, though this is in turn because humanity has a terrible reputation for exterminating any sentient aliens they can, with some exceptions like actual monsters who very much deserve to be wiped out like the Orks. Humans, by official policy of the Imperium of Man, are not supposed to tolerate the existence of Xenos.Surprisingly, there are exceptions, such as Necrons willing to use diplomacy, Eldar who are willing to teach anybody who'd listen, even minor states aligned with Chaos who would accept alien Chaos worshipers into their midsts. By the nature of the setting, just about anybody is this to anybody else, including splinter factions of their own species.