If this is about Ragnarok then i know nothing about it so please don't spoil, but if you're talking about Valkyries in God of War, then they are absolutely affected by difficulty. On Give Me God of War for example Atreus' arrows that you can spam do nothing to the Valks besides a tiny bit of damage, whereas on the lower difficulties guides on youtube showed Atreus' arrows could shoot Valks out of the air. That's a huge difference.
A few tips though, if the Valks fly up to land on you, time it and then next time run and roll away at the precise time. When they hover to lung at you throw your axe, when they hover to blind you all you have to do it turn around and it won't affect you because you can't see what she's doing, i think there's a quick 180 button, maybe down on the D-pad? If you have a particular move that you struggle to dodge, use the skill that's a shield ram, it interrupts any Valk attack and negates any damage you would take. I didn't use that one but it's a good skill to use if you want an escape clause when learning patterns.
Again, if you're talking about something in Ragnarok then i apologize but i ain't scrolling up just in case.