Dex (for melee)= Helps ALL offensive skills and abilities: how much you hit, proc, weapon skills going up, critical hits, etc.
Dex (for casting) = Helps regain concentration to keep casting while being hit.
Str= Increase how hard you hit, and normal weight issues everyone has.
Agi= Helps ALL defensive skills and abilities: parry, dodge, riposte, block, defensive skills going up, etc.
Int/Wis= More mana, spell casting skills go up faster, trade skills go up faster (will take the higher of the 2 into account when working on a trade)
Sta= More hit points (not much), wear down less when fighting, running, swimming, etc.
Cha= How much NPC's like you, the higher it is the more you can sell to merchants for and the lower you can buy for, the lower the charisma the less money you get from merchants and the more you have to pay for items.
NO arguing this! this is directly from verants nice little books they call players guides where they explain what each stat attributes itself to. Have a nice day and stop arguing about stupid stuff :o)