My favorite idea that you had was this one.

4 Points: Convert a cross Class ability into it's traited version (Flash would have blind on war etc)

The only downside is this can cause some balance issues. Overall it still seems pretty cool.

Another could be like

6 Points allows you to use one cross class skill from outside your base 2 classes. Drg with Raging strikes, BLM with IR and so on. Again balance problems but still cool.