Weakness is a double-edged sword in "Easter Wings." On the one hand, it's seriously bad. Adam is weak-willed and ends up "most poor." The speaker arrives in sorrow and endures so much that he collapses into line 15, "most thin"—and all because of Adam's weakness in the first place. But on the other hand, weakness is also opportunity. If humans didn't fall so low, they could never soar up to God like birds, to sing his praises and gain forgiveness. And Herbert emphasizes in lines 10 and 20 that it's also the journey itself, and not just the goal, that is full of hope and joy. Why else would he celebrate that Adam's fall will "further the flight" and that "affliction shall advance the flight"?
The speaker's weakness derives more from Adam's sin than his own sins. At least, that's what Herbert suggests.
Although God's punishments contribute to the speaker's weakness, according to the poem, God's strength allows the speaker to overcome it.