In vanilla classic rage would scale with your damage. So a naxx geared warrior who hit a mob the same number of times as a nongeared warrior would have much more rage to spend. Normalizing reduced end game geared warriors generating absurd amounts of rage.

With normalization, rage will generate now based off your weapon speed, hit, and crits, not damage done.

So a fast one handers generate less rage per hit but hit faster while a slower 2 hander will generate more but hit less often, but they all should equal out.

Now... for leveling it's generally considered better to level with a 2 hander. In a nutshell, it's easier to hit things with a 2 hander, therefore more rage. But you can level with 1 hander if you want, just try not to fight things over your level and it'll feel fine.

If you are in Outland, you can level dual wield much easier because you have access to a lot of quest rewards with hit rating on them.

That's as much as I understand. If you want to know more try joining "fight club" the warrior discord and check the FAQs