EDIT: Upon further examination, I'm not sure the Custom Traits feature actually works. I've tried using
"31:1:0" in an entry, which should, according to the trait listings, add Skill Category 1 to an actor's usable skill categories when equipped...And that's not happening.
I've also tried using 33:102:0 which should grant Skill 102 to an actor while the weapon is equipped. ALSO does not work.
I don't think the Custom Traits feature works at all.