Eveything modding is in the #modding category, though some things might be in the #modeling-animation or #scripting-code categories.
If all you want to do is to add a VFX to a wearable weapon, you don’t have to mess with animations (unless your weapon will have its own custom attack / animation, in which case, there’s an add-on for Blender made by a community member: Stonehearth Add-On for Blender (Animation)).
It’s also possible to attach a default effect to an entity in its json via the “effect_list” component.
(The Stonehearth's Modding Guide is going slow, but will eventually contain all that).