The Shield of Light was a resistance group founded during the reign of the Dark Lord four thousand years ago. Actually, the Shield of Light is a fringe militant group that is preparing against the return of the Dark Lord. The group believes that all mortal weapons in the world will ultimately be useless and it's only through the use of magic that such a victory will be won.
The original Shield of Light was a group founded in 2139 BC by the Orc Jirak, being the first group to present resistance against the reign of the Dark Lord. After the defeat of the Dark Lord and the global prohibition of magic, the Shield of Light ended up dissolving.
In the modern world, there still exists an incarnation of the Shield of Light, a secret organization made up of primary humans who seek to prevent the return of the Dark Lord. The rest of the world and the government see them as eccentric activists. They have both weapons and military technology as well as knowledge about prophecies and languages of other races.