Magnum Break Fire Attribute Bonus 10% instead of 20%

The description of magnum break says

5x5 cells, Fire property splash attack with ATK of (100+20*SkillLV)% and a +10*SkillLV bonus to HIT. Enemies hit by the attack are pushed back 2 cells. Drains 15 HP per use, but cannot kill character.
After usage, it adds a 20% Fire-elemental bonus to ATK that lasts for 10 seconds. After the cast the attack sequence is not interrupted.

through testing on a ranger and a marine sphere card on the test dummies, the added damage (arrow storm) on neutral element mob appears to be 10%, with full 20% only achieved on the earth element mob (but thats because of the 2x fire to earth multiplier).

I think the 20% is errornously coded as 10%