I would actually only place a handful of these royals in the category of handsome or beautiful. I think the majority of us have somewhat tainted minds about these royals. In many regards these royals are placed on pedestals. And beauty is often associated with royalty. But in reality very few of them would turn heads if they were not King/Queen Fill in the blank, Prince/Princess Fill in the blank. For example, back in 2005 just after Prince Sverre was born, I was anxious one day to log in and see the new pictures of the family. My mom happened to be in the room and she came over to look at the pictures as well. Her impressions of Mette-Marit were not thoughts of beauty in any way. My point is that since many of us here know exactly who these royals are we tend to look at them differently and we automatically view them to be better than the average person. But someone that doesn't have a clue who they are looking at might have a different opinion of that royal's looks
Despite many of these royals falling short in the looks department they have many other advantages that help them all out: great hairstyles, nice clothes, expensive make-up, and pricey jewelry. With all those things in a person's favor, anyone can look handsome/beautiful.
Another thing that I think may be the secret beauty weapon for some of these royals is confidence. Some of them, certainly not all, just walk and conduct themselves with a very high level of confidence which makes them look even better to us.