Xenon Damage Formula

This here is my entire point. Give him an Umbrella and see what happens. Instead of XenonWeapon * 4 * stats, it would be Umbrella * 4 * stats. If they changed the formula itself then you are talking XenonWEapon * 3.5 * stats or Umbrella * 3.5 * stats. That's how you could find out for sure which part was changed. It would make more sense to me that they would keep the numbers simpler and thus change 4 to 3.5 instead of changing 1.5 to 1.325. It's a 2 minute effort to get a definitive answer.

You can't change weapons to determine damage formulas, they're not inherent to the class, they're based completely on the weapon (not just the multiplier). Going from Energy Sword to Umbrella changes your damage formula from Energy Sword's to 1H Sword's:

Energy Sword Multiplier * (4 * Main Stat + 1 * Secondary Stat) * WATK/100 -> 1H Sword Multiplier * (4 * Main Stat + 1 * Secondary Stat) * WATK/100
Where Energy Sword's main stats are STR, DEX, and LUK, with no secondary stats, and 1H Sword's main stat is STR, with DEX as a secondary stat.