Read the dual pair’s enchant-triggered ability separately from Soul Crystal enhancements.
Dual swords have an enchant-triggered ability instead of the normal selectable Soul Crystal enhancement. Read the exact pair’s threshold and effect. The S-grade dual example below activates at +4 or higher; a stage-13 crystal is not its activation requirement.
This S-grade pair grants +15% maximum HP, +20% maximum MP and +30% maximum CP when enchanted to +4 or higher. These are maximum-resource bonuses, not damage percentages.
This A-grade pair instead grants +8% attack speed at +4 or higher. Do not copy the S-grade pair’s HP/MP/CP bonuses onto it. Both the pair and its enchant level matter.
Both pair descriptions also mention increased PvP damage. They do not, by that wording alone, establish the exact percentage or whether that component activates at the same threshold as the listed +4 ability. Do not assume a universal +5% bonus unlocked at +4.