I've already looked it up on Hercules Wiki, it says Post Xray Client would need to edit the .lua file. Reference: http://herc.ws/wiki/Adding_new_skills#Renewal.2FNon-Xray_Support
Q1: Where is the .lua file located? Client Side or Hercules Git?
Q2: If I wanted to make the skill available to every class like "Basic Skill" or "First Aid", what category/class name should I change it to?
Answered: Change it to Novice
Ex:
[JOBID.JT_MAGICIAN] = { [1] = SKID.MG_STONECURSE, [2] = SKID.MG_COLDBOLT, [3] = SKID.MG_LIGHTNINGBOLT, [4] = SKID.MG_NAPALMBEAT,
is Equal to Magician having Stone Curse, Cold Bolt, Lightning Bolt, Napalm Beat, etc.