septembering arms of year extend yes humbly wealth to foe and friend
It looks like that seasons thing is coming back again with the word "septembering."
The month, of course, makes us think of fall, September being the first month of autumn. So, we're going to say that the speaker's father is now in the later years of his life, getting ever closer to death (a.k.a winter).
We're sure you noticed also that September, which is usually a noun, is turned into an adjective describing "arms." This makes us think of the aging of the father's body.
Still, even though the speaker's father is aging, he's an all-around awesome guy, who gives generously to people he's cool with and people he's not so cool with.
than he to foolish and to wise offered immeasurable is
These lines take us back to the idea that the father really helped wake people up to being alive.
Notice how the poem turns "is," which is usually a verb, into a noun. "Is" is a "to be" verb, so it kind of makes us think of existence itself. So the father is giving people a giant batch of life itself. (Dude, we want some.)
He gives this to people who are smart enough to know what it is, and he even tries to give it to people who are too dumb to see it.