For me, a pluck is always preceded by a creep or collapse. Not a slow creep, that I could either reverse or let down, but a sudden relaxation of the wrong muscles when I'm still holding on to the string. If I focus on maintaining back tension, it usually prevents a second pluck from following the first one, but I don't really know how to stop the first one, since it doesn't happen very often and is always unexpected.
Don't know about the arrow showing stiff or weak, but the arrow always ends up missing to the right, usually high, and my right hand ends up flying away from my face.