how to decrease this skills Rolling Cutter and Cross Ripper Slasher?

[jpnazar 0]

how to decrease this skills Rolling Cutter and Cross Ripper Slasher?
battle.c
 

case GC_ROLLINGCUTTER:skillratio += -50 + 50 * skill_lv;RE_LVL_DMOD(100);break;case GC_CROSSRIPPERSLASHER:skillratio += 300 + 80 * skill_lv;RE_LVL_DMOD(100);if( sc && sc->data[SC_ROLLINGCUTTER] )skillratio += sc->data[SC_ROLLINGCUTTER]->val1 * sstatus->agi;break;