I think that the way they will end up nerfing it is taking a swing at it's duration. It can't get a nerf to damage buff since that would hurt all radiance sources, Bungie has publicly defended well's really amped health regen, and they purposely made it give damage resistance. The only way I see it being nerfed is either seeing it's duration take a major hit or reducing the sword's health value in PvE. (Remember that the sword gains more health based on resistance stat)