Yes, that's what I wanted to see. The shadow you're talking about is an independent picture element (layer "pen shadow". As such it is "burned" in (painted shadow), when you rotate it, it will rotate according to your rotate instructions and not according to the light. To rotate the pen with a "correct" shadow, rotate the pen and recreate the shadow. To create the shadow, you can use drop shadow effect, which works sometimes very well and that one is created by Ps according to parameters as shown by davescm, or you can use your talent to recreate a shadow. It may also be possible to reuse the existing shadow and to modify accordingly. A manual shadow is created by copying the original layer ("pen") and distorting accordingly. You fill it black, change the layer mode from normal to multiply, add layer transparency. If you can't get the shadow right by distortion alone, you can also paint some parts of the or the complete shadow. To get a soft shadow, you need to blur the shadow picture. And as shown on your picture, the shadow layer should be under the picture layer.
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