Skill usually means being crafty, able to execute something well. In some endeavors Skill is taken to be the utmost Goal, if you can move skillfully you prevail.

In Sumou Skill is secondary to Power. Just being able to move skillfully doesn't mean much, the key is Power.

Skill only comes into play in the form of Katachi. You must be able to preserve good Katachi. This is the meaning of Skill as expressed in Gi.