Technique levels (contains spoiler)

1-circle: can be used by a 1-circle mage or higher

2-circle: can be used by a 2-circle mage or higher

3-circle: can be used by a 3-circle mage or higher

4-circle: can be used by a 4-circle mage or higher

5-circle: can be used by a 5-circle mage or higher

6-circle: can be used by a 6-circle mage or higher

7-circle: can be used by a 7-circle mage or higher

8-circle: can be used by a 8-circle mage or higher

9-circle: can be used by a 9-circle mage or higher

10-circle: can be used by a 10-circle mage