Question About Melee Damage (need To Know In Regard To My Build Pls Answer ;-;)

I was wondering if whether the melee damage buff you get on armor (e.g. 18% melee) applies only to neutral damage, or does it apply to elemental damage? Or maybe does it apply to your highest damage (e.g. if your neutral is 100-200 and your earth is 200-300 it would apply to earth)?

 

99% sure it applies to all damage, but only with your basic attack, not spells.
EXAMPLE: I have a weapon that does 10-20 neutral damage and 0-10 air damage.
My basic attack does 15 neutral damage and 5 air damage on average.
My spell does 25 neutral damage and 15 air damage on average.
I put on a helmet that gives me +20% melee damage.
My basic attack now does 12-24 neutral damage and 0-12 air damage on average.
My spell still does 25 neutral damage and 15 air damage on average.

 

Thx :3