I think the reason that Eldritch Scion is suprisingly weaker than normal Magus is because they were super frightened at the idea of giving another class Charisma as a primary ability score, it already put Bards drastically high on the playable class just because you can do more out of combat just by talking the GMs ear off!
The biggest fix for me would be to change the "mystic focus" from 2 rounds to +1/4 level or something, even a minor boost would help I think.

(Sorry off topic, keep it up OP I love me some Magus!)