Nietzsche made a point about what he calls slave morality. The fact he decided to identify such morality with the core institutionalised morality of his time, christianism, is another point. While christianism do have compassion elements - as every religion not made by some psycho - doesn't really show itself as particularly peaceful one through the history.

There is no contradiction here. Master morality means valuing personal dignity and greatness, slave morality means valuing that which benefits the weak. The most violent and aggressive group in America right now are leftist "anarchists" who want everyone to grovel before their "social" values. The concept of slave morality does not refer to an inability to act, it refers to identifying with the weak, placing the cause of the weak over the cause of the noble and then justifying action on that basis. I can't see what's so hard to understand about this.