Age of Mythology

So, I'm only a tiny bit better than you. About 1100 in 1v1.

I've just recently gone back to playing Norse for the first time since the old EE days. Though I play Loki, not Freyr. I played a couple games against a friend, and after beating him, I had trouble figuring out exactly what he should have done to counter it. In his case, I think it came down to not following any particular build order in Archaic Age. Finding a good build order from one of the pros and practising it until you get good at executing it can be a major boon, if you're not already. Beyond that, I think it's helpful to keep in mind the basic broad strategy counter triangle. Rush beats boom. Boom beats turtle. Turtle beats rush. If they're rushing at you, try and get walls up—either full walls or just strategic walls that force them to go around obstacles and walk close to your TC or towers if they want to raid your villagers. Ideally you want to be spending less on defence than they are on military, and invest the rest into economy; get 2 TC before they can, get your eco upgrades, etc. If you've got good mobile units, try going for counter raids to force them to retreat their military. This is especially good if, like my friend in the game I played last night, you have access to Hermes and can mass a few centaurs. Hippeus work well too. Or anubites or sphinx. If they're like me, they're probably relying on their aggressive push to be the protection for their eco, leaving everything behind completely unprotected if you can sneak past.

That said, unfortunately if you're going up against 1400s as a 900 player, it kinda doesn't matter what you do or what they do. They're that much higher than you because they're that much better than you, when playing their preferred strategy. A 500 point Elo difference means you have a 5.32% win chance.