to gain the privilege of being a warrior didn't they have to go though some tourtures...ummm, trials first?
i have always felt that it was pretty safe moral ground to use the techniques of the enemy on them. no more, and certainly no less. if they were well trained they should have been trained to withstand that threshold of treatment.
Different nations, different rules, rituals, etc. Among us, children are taught from a young age to endure pain and not cry out. Even infants were taught not to cry. A crying baby could alert an enemy as to the location of the group. If a baby cried, the mother would pinch its nose shut. In order to breathe through it's mouth, the infant had to stop crying. While it sounds cruel, the baby wasn't hurt.
For older children, older warriors would instill in them the duties and responsiblities of a warrior by recounting war stories, deeds of valor and courage, and proudly displaying scars from old wounds and injuries. This still works today. There is a young girl in my clan who was always afraid to go walking in the woods, but every time we got together for a gathering, she and I always had to go walking together. When I asked her about it one day, she simply said, "I love the woods but I'm afraid of the monsters. But I KNOW that even the monsters are afraid of you!" Such sweet words to say to an old warrior like me.
That makes all of the hard work and sacrifice worth it.