Leadership increases own team's attributes and Battlecry decreases the other team's attributes. Both skills seems to be doing the same, just in opposite directions.
However, leadership actually has only an effect on str, agi and dex because the increase in vita and int doesn't increase health and spirit. On the other hand, Battlecry decreases all attributes and has also an effect on health and spirit due to the reduced attributes.
Did I get this right and if so, is this intentional or a bug?