Skill.

[In Zenyatta's voice the word is hollow and flat; he would like to summon some sort of disgust for that implication of admiration, but it seems a wasted effort, and he knows deep down that expressing it will not drive back the ache that still lingers within him.]

... I cannot change the past. I seek only to learn the truth, and to look into the eyes of the one who stole my brother's life, and understand.