Cure III
From HorizonXI Wiki
Restores target's HP
Learnable by WHM 21, RDM 26, PLD 30
On HorizonXI, healing spells reach certain potency caps (such as 75 HP restored for Cure II) and will only surpass those caps once a player's combined MND, VIT, and Healing Magic Skill reach a pre-determined "power". Viewing the below script, you can see what "power" requirements healing spells need to improve potency.
https://github.com/AirSkyBoat/AirSkyBoat/blob/staging/scripts/globals/spells/healing_spell.lua
The "power" formula is believed to be as follows:
(MND * 3) + VIT + (Healing Magic Skill * 0.6) = Power
As per the above link,
Cure II will only heal for a maximum of 160 HP until a player reaches a power of 300.