He's "weak" because he can manifest other people's powers in a stronger version, but doesn't have much power alone. Besides in a society where you are judged by appearance, I can understand why he has low self esteem.
Having low self-esteem doesn't explain why he has to blush literally everytime someone looks at him.
Blushing isn't something you can control. I had a male classmate who blushed way more than average (I think, he had idiopathic craniofacial erythema). Furthermore blushing can be a symptom of a social anxiety disorder. Low self esteem and social anxiety disorder often go hand in hand.
a little cheesy with a cliche weak protagonist w a special rare power tht basically nobody else has lmao
but i like the art ;;; i love the concept, i just wish the characters had,, a little bit more depth to them (especially eru he's literally the main character of a shoujo manga but a guy)