At the moment, my Dawn Warrior is in the mid/late 2nd job (50~60's). My skills at the moment are:

1st Job:
HP Boost - Max
Iron Body - Max
Power Strike - Max
Slash Blast - Max
Soul - 1

2nd Job:
Sword Mastery - ~10
Sword Booster - 0
Final Attack - 0
Rage - Max
Soul Blade - Max
Soul Rush - Max

Currently, I'm maxing Mastery, because I was more interested in Rage and Soul Blade/Rush. I know it's not following the book exactly, but it still works.

Anyway, I was thinking, after I max Mastery and Booster, I'll have FA left. If FA doesn't work with Soul Driver, it's pretty useless, isn't it? Now, I'm not sure if it does or doesn't work with Soul Driver, but if it doesn't, should I add my SP into Soul (1st Job) instead? I could max it and chuck the rest of the points in FA, since FA may be useless.

Tell me what you guys think.