[Namel]

Intelligence is much better than described in game. Every point of int seems to give about 10% more damage and healing power. In addition to that you get 10% more at ever 7 int. And 1 more turn to spell duration at 15 int. (Not to all spells tho, at least phantom duration did not increase at 15 int.)

Here is some quick numbers for level 3 magic poleaxe at diff amount of int:
Int Damage
2: 430
3: 470
4: 500
5: 540
6: 575
7: 670

So if you use lot of damage or healing spells int is very important.

I think attack is much better than defense. At least I usually hit lot more often than get hit so I use attack much more than defense.