Sa Haiyun is a lesser deity who brings fortune to those who seek it through her eyes. She is mostly worshipped by pirates in the Sea of Teishàn.
Sa Haiyun gives her worshippers the ability to see the world as they want, and to pursue their own dreams in whatever way they want as long as they benefit their deity by worshipping them. Basically, the deity offers religious freedom to the pirates and in turn, gifts them freedom over their own world by allowing them to follow their own desires.
If the worshipper wants money, they can pursue that money however they want, and the deity gives them the ability to see their cause as righteous. Just the same, if they want power over a group of islands, the deity gives them the ability to see their cause as just by giving them divine approval through a worship ceremony. It sets them apart because their gift from their god is "freedom of thought" instead of a specific thing like money, land, etc.
She and her worshippers aren't really understood by most.