its called a brit yitzchak. parts of the zohar are split among the people who come and everyone reads. usually refreshmnents are served. then …drum role… a small ornate sword/dagger is waved over the kid to destroy mazikim. what up.
I have never seen anything waved over the baby. In fact, the baby is not even present. The men read portions from the Zohar regarding berit mila and then eat so as to say each of the food brachot.There is no halacha that one must be 40. Many say that one must be 40 to learn Kabbala but the Chafetz Chaim and Rav Mordechai Eliahu say that this does not apply to just reading from the Zohar.