For the tidbit of information and the story hook I do accept having the debuff, was a fighter heavy weapon eldritch knight, the lack of critical seems a bit excessive it is much worst then being permanently blinded as you have disadvantage but you could play around that to get advantage or just get luck and double roll nat 20s. I think the debuff is fine but it should be modified to something less drastic as criticals are impossible or at least have some benefit for when you would score a critical that isnt extra damage like healing damage that would have been done, innate spell resistance, or better yet class specific debuffs and boons.
