The same co-efficency/talents is true also for damaging abilities btw.
Here is how I understand the thing.
The basic-abilities in the tree you spec in, are always better than the abilities in the trees you have not specced in. Core abilities are always considered to be fully specced in.
For example for Warrior Priest: No matter where you have spent your points, [spell]Healing Hand[/spell] will always be a good spell. It only scales by your rank and your willpower.