I don't think it is so much that you can take a sword to the stomach and not flinch, that's just a result of the mindset. I think the real idea behind it is that only in showing true unhindered compassion for another being, regardless of its initial intentions, do you bring about the means for real revolution (because you're breaking down the barrier between you and them and at the same time realizing the commonality you share). As soon as you pick up a gun you're participating in the game of violence which will undoubtedly end in bloodshed. You will never change the minds of those who are violent by confronting them violently. You have to shake them to their core with compassion and break down the separation between oppressor and oppressed, meet them on the same level - you will never do this with weapons - it will always be us vs. them unless you help them to realize their true potential by exhibiting it, being compassion and strength - real strength - the kind that actually matters.