Each endpoint for skills (specifically weapon skills) has an slot attribute. I'm currently tracking the slot attribute to make a build calculator and it seems to be changing values within the API. Not only that, but not all Elementalist weapon skills have a attunement attribute. Some of them have Specialization attributes when they shouldn't.
Examine off-hand Elementalist Dagger and Focus abilities.
Cone of Cold
Currently as I'm writing this, the slot attribute is set to "Weapon_1". Which is wrong. Cone of Cold is weapon skill 2 on Dagger. However, this value appears to be changing periodically? It took me quite awhile to figure out, I initially thought it was a logical error on my side but its appearing like this in the API. Sometimes it actually does read correctly and says "Weapon_2"
Cleansing Wave & Fire Grab
Right now Cleansing Wave says Weapon_5 but It has said "Weapon_2" and not only that. But it currently has a Specialization attribute it shouldn't have and it has no attunement attribute that it should have.