Mphyoi is correct, only start gaining prof at 1 level higher than your prof level. so ati doesn't gain light prof till level 46 or so
also if you didn't know, prof will allow you to hit the EE cap.
the prof cap being 80ee for tier 3, so the 74ee would only need 6 prof to cap it, whilst the 58ee with 8 int needs 22, i use 25 fire prof so I have capped both of them, you can see the 9 int influences the damage to deal more than the higher ee one because of this