I find a "Guide" must be as objective as possible, so for the skills( among other things) this is almost impossible !!
EACH gamer has his/her favorite skills and so his/her favorite skills are in his/her eyes the BEST skills and other skills he/she not used are "useless" ??
O no !
When a Guide only write about the effects of each level of each skill, that's objective
. But NOT if you go saying useful or useless or .... etc ....
So that's my opinion.
But I never expect a "perfect Guide", so no stress Lancet ... your guide is already big and full of information ! Nothing can be "perfect", fortunately !
I'm a little bit afraid that you go feeling 'sad' when analyse a game too much !! Then, I'm afraid, the Fun flow away of it, no ? 
But probably it's my feeling with a "game" : I only wish to have Fun, it's a Game, entertainment in my life, so for me no point of analyse a game in it's most detailed properties (for example with the % in damage values for the different enchantments, if they stack or not, ... etc etc ...) !
