What I did was I split "Holy" and "Dark" into four. On on hand, you've got "Light" and "Shadow" which represent actual photonic light and the lack thereof. On the other hand, there's "Divine" and "Demonic" which represent good and evil. Light and Shadow are opposites, meaning that they cancel each other out, Divine is only used for the plot-crucial macguffin, and Demonic isn't actually an element, as it's used to keep track of what enemies should be weak to Divine. So, in conclusion, Light and Dark can be moral light and darkness, or photonic light and darkness. At the end of the day, it all depends on the story you want to tell.