It was all that Mal could do to keep from rolling his eyes as he listened to his opponent pontificate. The kid may have been quite skilled in the 'Arts' of War, but that was all they were to him, Arts.
Mal would lay odds that the kid had never set foot on an actual battlefield before. He had never fought against an overwhelming foe, outnumbered and out-gunned. If he had, he would've shot Mal right between the eyes first chance he got, and saved his preachifying and his fancy sword for his corpse. Kid had some strange notions, that was for sure.
Dead was Dead, and it didn't really matter much to a man how he got there, he was still Dead.
To the kid, though, this was all some grand game, with himself as the Hero, upholding Truth, Justice, and the Alliance Way. He had probably spent the War tucked away safe in some Planning Center, reducing men to numbers on view-screen. He had clearly never faced someone without having superior numbers and firepower to back him up. It was easy to swoop down and kill unarmed folk, after all, when you had the money and manpower of the Alliance behind you. Easy to give the order, easy to murder little girls, and easy to pretend you were making the world a better place by doing those things. You had time for fancy-smancy swords and strange notions. Time to build elaborate fantasies to justify your actions, time to pass judgment on other folk while turning a blind eye to your own faults.
Kid just didn't understand what fightin' for a Cause really meant. His Cause was all abstract, full of unreachable dreams and fancy words, with no room for him in it. Heck, he didn't even really know what his Cause was, just trusted that a group of politicians knew better than he did.
Mal, on the other hand, he knew what his Cause was. It was Book, killed defending his home. It was Wash, dead trying to bring his ship down safely. It was Zoe, with that empty look in her eyes and vengeance in her heart. It was Jayne, terrified of the Reavers but willing to fight anyway - without pay, even - just 'cause Mal asked him too. It was Inara, leaving the safety an' protection of her Guild to fight a hopeless battle beside a bunch of no-good thieves, smugglers, and 'fugees. It was Kaylee - sweet, innocent little Kaylee - picking up a gun to defend her crew-mates. It was Simon, leaving behind everything he knew to rescue his sister, disregarding his Oath to take up arms an' fight for the crew. It was River - damaged, crazy River - as deadly and dangerous as a poorly-cleaned gun. It was the folks on Miranda, just lying down to die because some politicians somewhere got the notion into their fool heads that folks could be made 'better'. It was all the victims of the Reavers, their worlds and bodies ripped apart at the whim of savages. Hell, it was the Reavers themselves, innocent folk who woke up monsters through no choice of their own.
Mal's Cause was to make sure there were no more Mirandas, no more River Tams, and no more Havens. It was real, needful, and within his grasp. He didn't want to die, but if it came to that, this was a Cause worth dying for. His Crew, his People, his Family - they were willing to fight and die with him for this, so that he could get the word out, and he wasn't going to let their sacrifice be wasted.
Perhaps it was time for the kid to understand what his Cause was really all about. Let him see the secret that he had sacrificed so many lives to protect. Let him see what his much vaunted Honor was really all about, what his so-called 'Better World' would be built on.
Time to grow up, kid, life ain't no vid game full of Heroes and Villains and Grand Quests. It's gritty, ugly, desperate, an' it's all we got - no reloads, no second chances.
As the boy came at him with his fancy sword, thinkin' he was helpless, Mal moved.