(Devs) Dual Wield Mastery Trait name?

[Jgwman]

Does anyone, in particular someone at AH, know the programmatic name for the Dual Wielding Mastery trait? I was working on a mod, and putting together a temporary scripting reference, and I've been trying for a while to guess the name of this trait. I managed to guess all the other traits, but I can't guess this one. I've tried many combinations including:

SpoilerShow

dual_wield_mastery
dual_wielding_mastery
dual_wield_proficiency
dual_wielding_proficiency
light_weapons_mastery
light_weapons_proficiency
one_handed_mastery
one_handed_proficiency

and a good many other variations. If anyone knows, or has any ideas, I'd much appreciate it!