Which primary skill is better?

So, in the fifth game, while in the third... (well, if you don't see the difference between 3 and 5)

Oh my god, it seems that in the fifth game, attack increases the defense of troops, and knowledge increases the damage to units:D :D :D ?! The meaning is the same, isn't it? It's the same as discussing, for example, the dexterity parameter in the first Diablo and the second - there's no difference.