It takes on a life of its own

They do not dread Saul or even Yahweh, whom we would expect to be the greatest object of concern because the deity would be the activating force behind the harm in the malediction should it be breached. There is a definite sense that the troops are treating this curse as an independent entity that is not only to be feared but also to be respected precisely because of the fear it inspires. Here, the curse operates on the threshold of hypostasis. It is evolving into an independent entity.— Cursed Are You!, page 112

<idle musing>
As she will note a bit later, the ANE world even had deities that were basically curses come to life. Once uttered, a curse took on a life of its own, as did a vow. That's why Proverbs says not to make a vow lightly...words matter.
</idle musing>