So the weapons of sorrow such as thorn, Bad juju, malfeasance, witherhoard and osteo striga, are weapons affiliated with the darkness and said to be guardian killers. It would stand to reason that if the hive have the light these weapons should do extremely well against them. SO , I propose that these weapons be buffed specifically against enemies wielding the light.
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I'm pretty sure the red death was the only one specifically called a guardian killer, and that part of the description was even retconned. The O.G. thorn would drain people of their light, but that became lumina