What type of feature is a life skill?

In Chapter 5, Aristotle explains that the soul has three types of features:

(1) Emotions (anger, envy, joy, etc.).
(2) Capacities (the capacity to be angry, the capacity to be envious, etc.).
(3) Dispositions (tendencies to feel an emotion intensely or not, e.g., to be violently angry rather than barely angry, as when we say "he has an violent disposition").

(Note that in this context, "disposition" is not the technical term that analytic philosophers often use to mean a causal power. "Capacities" are more like powers here. Dispositions are more like tendencies.)

As for the skills that help us live successfully (and the contrary skills that help us live unsuccessfully), which type are they?

Aristotle first explains that they are not emotions. We are not good or bad because we have certain emotions. On the contrary, we are called good or bad because of our emotional skills. E.g., I am not a bad person just because I feel angry. I am a bad person if I don't handle my anger well.

Similarly, we don't choose to have certain emotions. Anger, envy, joy, and the like often arise quite naturally. But skills involve choice, so skills cannot be mere emotions.

For the same reasons, the skills that help us live un/successfully are not capacities either. We are not god or bad because we have the capacity to feel anger, envy, joy, and so on. We are good or bad because of how we handle our emotions.

That leaves option (3): dispositions. The skills that help us live un/successfully are therefore dispositions --- tendencies to feel emotions in particular ways and act accordingly. These skills belong to the genus of "disposition" (tendencies).