How common and expected is it to have published papers or patents as a Master student in Europe?
While it would be a good indicator of research interest and definitely a good merit to have published prior to graduate studies, but I have never heard of it as a requirement. Definitely not at my home university, but also never from my friends and colleagues at other universities around Europe. 

Also I would venture to guess patents are very rare at Masters level students, as it's not as common for universities to apply for patents, as it is in the U.S. The only people I know whose work ended up in some form of a patent application were my friends/classmates who did their thesis work at a company. 

Also to answer your question, I don't see why it would be bad to have a patent in your resume, if anything it shows interest in the business side of things. Whether it weighs as much as a publication is difficult to say, however. Practically, it depends on the admission committee, or the group leader for the position you are applying for.