I don't think that it should be nerfed, But I have an idea that would change how the weapon is used. Due to the lore behind the weapon, it being corrupted, I think that there should be some sort if negative effect on the wielder if they use the weapon. I'm thinking along the lines of something like the chaos blade in dark souls; as in, a small amount of health is lost when firing the weapon. It would offset the DoT, and force the wielder to consider their shots that they take. From a lore perspective, the corrupted nature of the weapon means that a guardian's own light is used to create the signature thorns that it fires.