I think the warning about not becoming arrogant is important.
It's especially relevant because the sword is from the era of the people who had this tech and fell - cause they lost track of ethics.
It did not criticise the killing - just the way and the theatrics. I think it was the right move to kill the scientist, but he should've just lopped off his head. Giving in to emotions is not good.
It's not about morals - it's about self control.