Suggested by iKnowledge Euron Greyjoy is a tough guy who can fight well with a sword. His savage fight style makes him rather unpredictable as well. Still, he won’t be able to handle Fingolfin. Fingolfin was able to fight on par with the mighty Morgoth who is as large as a mountain. Fin may have lost, but I don’t think Euron would do nearly as well. The difference in their physical abilities is quite drastic and so that would be game over for Euron. Fingolfin wins.
Suggested by iKnowledge Fingolfin is a powerful Elvin warrior whose strength and durability are uncanny. He was able to do battle with Morgoth for a long time and put up an admirable fight. It would take a little while for Wonder Woman to take him down, but she has time. Moreover, her speed is on a completely different level compared to Fingolfin so the odds of a successful counter attack are slim to none. Wonder Woman wins.