Fan Casting Afraid of Their Own Strength in Sort by Tropes

For whatever reason a character (usually a hero or Anti-Hero) is worried about doing more harm than good whenever they use their powers or abilities. Sometimes this only causes a healthy amount caution and stricter set of self imposed moral rules, occasionally it can get to the point of being Willfully Weak and using Power Limiters but sometimes it's so bad that they are petrified with the fear of what could go wrong to the point of a Refusal of the Call, 10-Minute Retirement or becoming a Retired Badass.