We were on the Magic Norway and Norway/Iceland/Scotland B2B last year and I brought jeans, pants, leggings, long and short sleeve shirts, a few cotton sweaters and an insulated, yet light jacket. I brought hats and gloves, but we didn't really need them. The weather was never warm enough to wear shorts IMHO. I also brought a pair of keds and a pair of TOMS sneakers which were durable enough for what we did which was mostly walking through the towns, plus a hike to a glacier (which wasn't terribly strenuous). I brought a few maxi dresses and wraps for the evenings because I find them comfortable and easy to pack, plus I didn't really go outside much at night. Though some people still dressed up for formal night, I would say people dressed more casually for dinner on these cruises than I have seen on Caribbean and Bahamas cruises.
I completely overpacked for our trip and learned my lesson! If I were to do this cruise again, I would bring about 4 washable outfits (except, perhaps the sweaters) and two or three things I could wear in the evening, plus no more than 3 pairs of shoes and do laundry on a sea day. I ended up lugging around at least two suitcases filled with clothes we never wore.