It the purely mechanical sense, yes. I know the weak points on a human body to kill quickly and with minimum danger to myself.
Ethically, it would be dictated by the situation. Could I kill someone I knew personally? No. Would I kill for money? No. Would I kill if someone was threatening people I cared about with lethal force, or meant them permanent harm? Yes. In that situation, I would have no qualms about killing that person. They threatened people I love, and if it is a choice between sparing their life or saving my friends'/familys', then there is no choice at all.
Just as a point in clarification, when I say I could not kill for money, I mean in the sense of in a civilian envionment. If a war broke out and I was conscripted, or I joined the armed services voluntarily, then I would kill, but it would sit very heavily on my concious. If wounding or maiming was an option, I would prefer to wound or maim.