The above berachah (blessing) was intentionally left unfinished because it represents a blessing that does not exist: the berachah for the mitzvah of tzedakah (charity). Why does this mitzvah, which ranks so high among the mitzvos, not merit a berachah?
One reason is that a berachah is supposed to be said with meditation and concentration on its words, reflecting on the infinity of God and His sovereignty, and the significance of our having been chosen to observe the mitzvos. Unfortunately, it is easy to mumble a berachah without giving it the thought that it deserves.
Tzedakah must be performed promptly, without any delay whatsoever. If someone needy requests help from us, we have no time for meditation. The needy person needs help without delay and should not be made to wait while we prepare ourselves to perform the mitzvah, and certainly should not be sent away to return at a later time.
But why did the Sages not formulate a berachah for this wonderful mitzvah and simply specify that it should be said quickly and without meditation? That kind of a berachah is hardly worth saying.
The absence of a berachah for tzedakah thus teaches us two things: (1) tzedakah should be given promptly, and (2) berachos require adequate time for meditation and concentration.