He wears sunglasses with such swag that people can't help but notice him.

swag 是俚语，原指"战利品"或"赃物"，后来引申为"酷炫、有范儿"的意思，形容一个人自信、有魅力的气场或风格。在这里指戴墨镜时展现出的那种潇洒自信的感觉。