Redvex wrote:Bonuses on enhancement line only affect your base buffs value, and do not change spec buffs value.
Conc is only affected by piety.

Correct?

Correct.

Bonus in enhancement improve base buff untill you get your spec level to the buff level. More point has no effect. With 40+5 and 40+15, a level 45 base buff will give the same bonus.
So it does not change spec buffs because your skill has already reached the level of the spell.

For piety, +1 piety = +1 concentration point.
You can check it by adding/removing some parts of your stuff with "+Piety" on it.