[…] The glory is fled,the nobility of the world ages and grows sere,as now does every man throughout the world. (88-90)
These lines compare the decline of the world's nobility to the aging of a single person. The idea here is that the world's nobility doesn't just go out like a light. Instead, it slowly fades away, pathetically. The same is true of a person, who, in old age, withers toward death.
Age comes upon him his face grows pale. (91)
Instead of saying a person ages, this line speaks of age coming upon a person, like an independent force that overtakes him. We have to say, it's a little terrifying.
The graybeard laments. […] (92)
This guy is so old, he's literally nothing but a gray beard. Now that's aging.