Suggestions for RPG development.

Here is my suggestion:
In addition to the unique abilities of classes, we should add sort of universal ones that any class can learn. With each level up, one more ability could be learned. Example:

1. Basic Endurance - provides an additional +3 health for each level up
2. Advanced Endurance - Automatically annihilates 5% of damage.
3. Absolute Endurance - provides another +2 health for each level up and automatically annihilates 5% of physical damage. Bonuses stack with basic and advanced endurance.

,or:
1. Basic Concentration. Increases mana regeneration by 10%. While concentrating, the character becomes more vulnerable. The concentration effect disappears upon the first attack on the character.
2. Advanced Concentration. If a character is hit by a magical attack while concentrating, 10% of magic damage is annihilated.
3. Master Concentration. Increases mana regeneration by 10%, stacks with Basic and Advanced concentration bonuses.