The Pristine Side of the Severed Union was reserved for those who had earned statuses that rivalled those of the Factions. The means of earning said status didn't necessary matter, but they also had to form some kind of credibility in the eyes of the Factions that mattered – Eaniss' and the Mad Bishop's especially.
This was the reason why Riba, the Diviner wasn't afforded a space on this Side even with his exceptional abilities.
The Saint's Chamber had done much for the Factions. They frequented it a lot, having their high-level artefacts appraised and tempered to their niche needs.
Indeed, most of the Saint's Chamber's prestige was because of one individual, a blacksmith with a Hidden Class that granted him extraordinary abilities. He was one of the very few people on Aigas who could create Transcendent grade artefacts and weapons for instance, which was a trait that attracted most to him more than his ability to alter all manners of tools.