I'm also having this exact same issue. I think it happened after I killed either some Frost Atronach's or an Ice Wraith. Maybe its the light source effect from taking frost damage and its not going away? I'm trying to see if following any of the methods from the thread TUTORIAL: REMOVING UNWANTED MAGIC EFFECTS FROM THE PLAYER will work. Edit: After looking over my load order I think I've found the culprit, Immersive Spells and Light - Spells emit light, which effects atronach's and some other monsters. I still need to test whether this is the true culprit, seeing as I reverted to an earlier save because the thread linked above didn't solve the issue. But I did test before the save revert and confirmed that Frost Atronach's were indeed causing this player emitting light bug upon them hitting you.