A question on Expertise

Until recently, I did not put any points for Expertise. However, after browsing thru this site, I learned that, and I quote:

"Every rank in Expertise reduces energy costs on any attack skills, preparations, or traps by 5%... It is highly advisable to have a high Expertise rank as it not only increases the power of all its linked skills but also reduces energy cost on other attack skills as well, even from other professions or attributes"

So I redistributed my attribute points and reached 10 for Expertise. I expected that the energy costs for my skills will be greatly reduced. However, when I checked the skill costs, they remain unchanged. For example, Troll Unguent still costs 5 Energy.

Is my understanding of Expertise correct? Is this a bug?

Thanks in advance

Troll Unguent was just an example, right? Because this one is neither an attack skill, nor preparation nor trap.

The cost will be reduced if you cast it, it just doesn't display on the skill description which shows base costs.

4 ranks will make a 5 energy skill cost 4, 10 cost 8 etc.

What Kari said. The skills description does not change but the skill does indeed cost lest. You have to watch the energy bar very carfully. Move the points out of expertise, use troll ungnet, watch the enegery bar. Then move the points back into expertise, repeat the above and you will see a difference.

(maybe it should, like damage and duration change when you raise base attributes)