TwoSix
Master of the One True Way
It boosts the average smite damage by 17% (from 4.5 per die to 5.25). It's not going to break anything.....
Guys, I'm a complete idiot. I should have double-checked the character sheet before posting.
Yes, you're right. It is the great weapon fighting style, not the Great Weapon Master feat.
Boy, do I feel dumb now.