isn't the "Number scale" for Fire/Ice/Earth/Wind spells only cause NA localization team believed we would have trouble telling the diff between a Fire spell & a Fira/Firaga spell (like they are in most other FF games)? that aside I'd go with the assumption power of welder casting it has some sembolance on its STR (Fire 3 from a novice could be as strong as fire 1 from a master)