Expertise

The Expertise attribute reflects a Ranger's skill when using non-spell skills. This is a primary attribute and may not be used by secondary rangers.

Guild Wars Description
For each rank of Expertise, the Energy cost of all of your non-Spells decreases by 4%. Several skills, especially those related to Energy costs and skill recharge times, become more effective with higher Expertise.

General Description
The Expertise attribute increases the spamability of non-spell skills by decreasing the cost. Expertise skills are used to enhance other skills and have an all round selection of skills.

Associated skills
Expertise will enhance these listed expertise skills.