The Sun's Ichor was an extremist Mercalan group predating the Church Knights. A group of vampire hunters lead by a Glykin named Azorus, they would often gag, rack, and 'bake' vampires in the sun on top of high roofs. The brutality behind their methods, as well as doing this to a few people who weren't actually vampires, caused faith in Mercala to shake until the Church Knights were created. The Church Knights denounced the Sun's Ichor as the violent monsters they were, and the law of the land hunted them down, effectively disbanding them.
(from IG Lore)
Azorus, the leader of the Sun's Ichor, would also force-feed his own blood to the vampire. Watching them shiver, and scream in pain because the Glykin's blood is extremely toxin, and hazardous to the vampires to drink.