fallible, frail, imperfect, weak -- (wanting in moral strength, courage, or will; having the attributes of man as opposed to e.g. divine beings; "I'm only a fallible human"; "frail humanity")
delicate, fragile, frail -- (easily broken or damaged or destroyed; "a kite too delicate to fly safely"; "fragile porcelain plates"; "fragile old bones"; "a frail craft")