If I was going to do it, it would go something like this:
Keep the whole current system as it is.
Add two attributes per "constellation" for a total of six
The attributes don't affect Health, Magicka or Stamina
They give small bonuses because it is unbalancing the current game. You have to play at a higher difficulty to keep around the balance.
You get two (2) points total each level to increase any of the following, either two attributes by one point each, or one attribute by two points.
Warrior attributes:
Strength
Endurance
Mage attributes:
Intelligence
Lore
Thief attributes:
Agility
Charm
Attribute descriptions:
Strength
- Increase carry weight
- Increase damage with all weapons and bash
Endurance
- Increase effectiveness of block
- Increase effectiveness of armor
Intelligence
- Increase effectiveness of spells
- Allow certain unique quest endings
Lore
- Increase effectiveness of magic items
- Allow certain unique quest endings
Agility
- Increase damage with all weapons but not bash
- Increase movement speed
Charm
- Increase effectiveness of Speech
- Allow certain unique quest endings