I thought i knew how the abilities system worked (which ones affected just a unit, all the stack, only work when the leader is the commander...) but it seems i still have some doubts

On a thread on the Spanish sub-forum Coregonas has pointed me to the fact that the tooltip of the Artillerist ability states that it affects all the stack where the leader is (as i already knew) and... also all the stacks on the region if the leader is the most high ranking.
I was not aware that a leader ability could affect more than one stack and it makes me wonder how it works and what abilities function like this.
For example, on the battle report, the higher ranking leader of your side on the region is the one whose portrait appears on the top left corner... can i suppose all his special abilities (well, the combat ones at least) will apply to all units on all the friendly stacks of the region during battle??? Or only some abilities work like this??
And what about the offensive /defensive ratings of the overall commander??
I thought they would apply only to his own stack but maybe i'm wrong

Do this ratings affect also other stacks?? How??
Thanks in advance and regards!
