Student or Learner
"On the other, the Virgin Mary is portrayed as a young queen with her face painted and wearing a crown and a fancy blue dress. Which in the German artistic tradition make her beautiful (Morrall 1998, p. 3-4)"
Oh right, understandable?
First, you probably mean "On the other hand ..." Whether you need "hand" depends on the previous content.
The second clause isn't a sentence. In academic writing (perhaps always) you should try to avoid separating a subjunctive clause as a new sentence.
You mean "... a fancy blue dress which, in the Germanic artistic tradition, makes her beautiful" (Morrall 1998, p. 3-4). (The quote doesn't include the citation).
If Morrall actually wrote that sentence, then you should write it as you find it and put quotes around it.
If you are paraphrasing, you don't use quotes, but you still cite it as you have done.