Welcome to Elemental!

Try this: http://www.gamefaqs.com/pc/954860-elemental-war-of-magic/faqs/61009

A summary:

 -Strength: "Increases attack"
     Specifically each point of STR over 10 gives you a 10% increase in your
     attack rating, or each point under 10 a 10% penalty.
-Intelligence: "Increases your chance to hit with offensive spells as well as
  damage done"
     Each spell has its own formula for how INT increases the damage, usually
     somewhere between .1 and .3 extra damage per point of INT.
-Charisma: "Affects cost of recruiting champions"
     It doesn't say this explicitly but I imagine it works like STR and DEX
     where each point over 10 gives a 10% discount and each point under 10 a
     10% increase in cost. There are also one or two spells that factor in
     your CHR.
-Dexterity: "Increases defense"
     Works just like STR, each point over 10 gives you a 10% increase to
     defense, and each point under 10 a 10% penalty.
-Wisdom: "Determines number of action points it takes to cast spells in battle"
     Um, no. After character creation you will never see the word Wisdom
     again. This is your Essence stat, and it equals the max mana you can
     have at any given time. Casting a spell is a flat 2 action points.
-Constitution: "Determines hit points"
     You will have 1 hit point per point of CON.

Unfortunately, the only stats that matter for the average hero is strength, dexterity and con. Boring, really.