When you heal a friendly target that is at 100% Health, you have a 50% chance to apply Major Courage, increasing their Weapon Damage and Spell Damage by 258 for 10 seconds.
The Spell Power Cure set is part of the Imperial City DLC. It drops in White-Gold Tower in the Imperial City. Each set item is bound on pickup. You can acquire light armor, weapons and jewelry of this set in the Xivkyn motif style.
If you need more information about the Imperial City, make sure to check out the full Imperial City Guide