Expertise

Overview

 * Expertise is the primary Attribute of Rangers, and thus only accessible to them.
 * Each point of Expertise reduces the energy costs of Attacks, Preparations and Traps.
 * Expertise also works on the skills of other Professions that fall into one of the affected categories.

Skill Cost Modification By Expertise
Same data displayed differently to show its pattern of "-1 pyramids": This has a Relative Increase of 15,51 so you basically use 14-15 Expertise depending on what the skills cost that you use most.