So when you beat your first dragon then you go to the greybeards and go on. But While your there you can get as high as you want with your stealth or one handed or archery or even two handed if you have the patience. So How i did it was i got a steel dager and after i learned to shout the greybeards just walk around in their temple. So what i did was sneak behind one and just slice at him till he went down. But he did not die because you need them for the story. So he regenerates health and you can just keep doing it. I did it with lots of weapons including a flaming battle axe. So any weapon will due.

BUT make sure that you are not noticed before you attack because the greybeards will kill you if they do. So Save often and have fun.