Hi Jason, to skill up a club, you have to fit them first by selecting a Club then go to Enhance, and tap the Fitting. After Fitting a club, a space for skills will show. To skill it up, select the club again from the inventory > tap the enhance button > and Skill up. By the way, we made a tutorial regarding Skilling up a Club, this also can help you to know more about this matter. You can watch it here to the link we will provide below:
https://www.youtube.com/watch?v=_2c8W84a7hc
Jason Fricke