Some people say that penis should be pointing upward. but if some ones penis erection is fine but little be inclind to downward is that a sign if weakness? penis itself is straight with not much curvature.

Penises come...: Penises come in all sizes and point in directions from a little below the horizon to a bit above the horizon. Of course, comparing to the horizon only makes sense if the person is standing upright. He should realize that a penis has a mind of it's own and often points where it wants to point. That means overthinking about one's penis can interfere with the penis.