The Pirkei De’Rabbi Eliezer (Chapter 32) writes that when the first night of Pesach arrived, Yitzchak Avinu called his son Esav and told him, “My son, tonight the Heavenly angels are singing praise to Hashem. Tonight, storage houses of dews are opening. Prepare delicious foods for me so that my soul may bless you.” On this night, Yitzchak Avinu blessed his son Yaakov with ten blessings and Yaakov Avinu emerged from Yitzchak bedecked with blessings like a bride and groom. A Heavenly dew descended upon him, his bones widened, and he became mighty like his brother.
Based on this, the great Rishon Le’Zion, Hagaon Rabbeinu Yitzchak Yosef Shlit”a, writes (Yalkut Yosef-Pesach, Volume 3, page 62) that one should bless one’s children and other members of the household on the Seder night since this is an auspicious time as gates of abundance open and creations in Heaven and on earth sing Hashem’s praises. He quotes several Acharonim who writes likewise. Although the primary reason why we bless our children on Shabbat nights does not really apply on Yom Tov, nevertheless, there is a special reason to bless one’s children on this night, as we have written.
Indeed, Maran Rabbeinu Ovadia Yosef zt”l would bless all of his children and grandchildren on the Seder night amid much love, affection, and joy.
The Rishon Le’Zion further quotes from the Sefer Bet Aharon that on the Seder night, one may request one’s needs from Hashem and one’s prayer will be accepted. He quotes the Sefer Netivot Shalom who writes that on the Seder night, one can change one’s fortune from bad to good and one can become freed of all one’s suffering.
Maran Ha’Chida writes in his Sefer Chomat Anach (Tehillim 111) in the name of the saintly Ari z”l that all of the miracles performed for the Jewish nation are performed through great brilliant lights (this is a spiritual idea that on this night, Hashem’s Heavenly mercy is awakened even more than usual and it is an auspicious time for miracles and wonders) and it was established eternally that these Heavenly lights would shine every year on this night and at that time, a great salvation shall arise for the Jewish nation.
In his Sefer Aleh Shur, the famed Mashgiach, Hagaon Harav Shlomo Wolbe zt”l, explains that which we exclaim in the Hagaddah, “In the beginning, our forefathers were idol worshippers and now, Hashem has brought us closer to His service.” The question is: Is it only now that Hashem brought us closer to His service? This happened some three thousand years ago!
He explains that our Sages are trying to hint to us that at this exact moment at the Seder, Hashem is taking each one of us and is bringing him closer to His service. This holiday is not merely a commemoration of what once was; rather, every year at this time, the Heavenly lights that shined brilliantly for our forefathers in Egypt and if we merit it, we can also be precisely like those who left Egypt.