When The Upright Society of Civic Wizards was formed and grew in power, many of the dangerous lone sorcerers and witches were slain or brought to heel and forced to join the Society, but many more retreated into the wilder areas of the countryside or went over the borders into other countries, where they proceeded to make the lives of the local people miserable at all levels. The local peasants and traders were being extorted from, and the knights and nobles were unable to do much about it for fear of ending up as a small purple teapot or something of the sort, until a knight who was visiting the Sorcery Springs Geyser Basin strayed from a boardwalk and fell into one of the cooler springs, which is why he lived and managed to get out instead of being boiled to death. On his way back home he was attacked by one of the rogue masters of magic, but his armour repelled the magic when normally it would not have done, and he drew his sword and sliced off the head of the mage despite the mage throwing up a force shield to protect him.
Realizing that the source of his magic proof armour was the spring he had fallen into, he told his closest fellow knights and they went to the pool and poured the water over their armour and weapons, before going after another rogue sorcerer. When they successfully slew him with only one of their number getting a minor wound, they formed the Hexanjager Order there and then, an order dedicated to taking down the wicked witches and malevolent mages through non-magical means. As more and more of the unwanted magic users were slain, more knights joined their order, and the peasants and townspeople and traders welcomed the new order as their protectors. The area had been known as The Badlands or The Madlands because of the activities of the unwanted magic users, but now it became known as the New Lands. Trade was up. Taxes were being paid properly. Food could be grown safely. As time went on, the Hexanjagers found that even when they wore no armour, no magic could effect them or be cast by them-and that included healing magic and other good magic. Magical weapons lost their power when held by a Hexanjager, and small wounds might easily get infected and turn deadly without healing magic.
Their members being angry because of this, the Order turned unpleasant and didn't just ban black magic, but all magic in their territory. There was no way they would allow those they considered beneath them in the social order to make use of healing magic or other magic for themselves. Brands were forged, soaked in the anti magic spring, and when they caught any magic users, even those just passing through, they were branded on the hands, feet and mouth to prevent them casting spells for the rest of their lives, even when fully healed from the branding. Once they had been the protectors of the community, cheered to the rafters when they slew the necromancers, insane sorcerers and other magical menaces that plagued the area. Now it was the local healers and the users of grey and white magic, magic used to heal people, find lost things, build houses and herd flocks of animals that they came after, making life much harder for those under them. Wands, amulets and the like were confiscated and burned, potions prohibited and the use of the smallest and most useful spells were punished by branding or worse. Once the protectors of the people, now they are hated by most of them.
Hexanjager armour is proof against all but the strongest of spells, and whilst Hexanjager weapons have no magical attributes, they can cut through magical force fields as if they didn't exist, but the price of such power against magic is that one is unable either to cast it, or have good or neutral magic cast on you even when you are not wearing armour. Which means that small wounds can lay you low or at least be very draining. In our non magical real world, the equvilent would be somebody who was immune to all manner of poisons-but also no medicine would have any effect on the person when he or she did get sick.