well, I did lot of side quests before getting Spirits of Rage, so thats propably why I have it on lvl2 only(I started to use it much later then I should I guess) ...
Other than that, I did everything you suggested here..
(fighting all mobs in Darion, all quests I was able to do, all gold gathered, leadership flags, items..)
Still seems strange and unbalanced :/ Just because I didn`t level Spirits of rage enough, I`m screwed? Stilll, you should be able to fight normal mobss with just army and some spells.. Guess I will have to start new character and get Spirits of rage as soon as I can, so I can level it up as soon as I can..