Power is influence. A guy with a gun has a lot of power, or at least thinks he does. A leader with public speaking skills has power. Power is always a two-sided equation. Something or someone has power over someone or something else. That is, a king without a kingdom isn’t very kingly. Our speaker’s life is like a gun, and so we know that she has power. Our speaker is the one in control of language in this poem, and so she has a certain power over us. However, the scary thing about being in power is that it can be taken away at a moment’s notice. We watch our speaker struggle to gain control throughout this poem, and we watch her serve a far more powerful "Owner" and "Master" by guarding him as he sleeps.
The speaker’s anger makes her feel very powerful; however, without it, she is confronted with her own weakness.