Byregot's Brow is better than Byregot's Blessing when your Inner Quiet number is on the low end of the scale - from 1 through 5. At 6, the two moves are equal in Efficiency. At 7 through 11, Blessing is better. Brow starts out at 150%, but only increases by 10% for every IQ stack beyond the number 1. Blessing, as you know, starts off at 100%, but increases by 20%.

On top of that, with Blessing being useable on Excellent, Good, AND the ultra-common Normal, it is far more useful than Brow, which is only usable on the rare Excellent and Good conditions.

I can see Brow being useful if you got really unlucky with your Hasty Touch spam, or if you are just now leveling a craft up and did not have good gear from 2.x .... but other than that, it is not a very useful move at all.