I am porting my 3.5E wizard into 4E and he used to have a dagger with a prism in the handle as the focus for Rainbow Pattern. I thought the prism could be my "orb" implement but I wondered if you were allowed to have an orb and a weapon both.
That sounds like the mechanically approved way for me to do what I want to do. Seems like my judgment causing me to post this as a question was correct; having both an orb and an implement is such a mechanically broken idea that they believe it should cost you a feat and the side benefits that an orb or staff normally give you. (Assuming the only effect of Arcane Implement Proficiency [light blades] is to let you use powers with the Implement keyword.)
Well, the wizard I am porting over had a 10 in Wisdom anyway, so if I can't use the Orb and dagger both I'll just leave it at 10 instead of switching it with his 14 in Con.