In an article “Hand Signs of the Jews” on the Chabad web site, I found this explanation of using the hands in blessing the Candles — as so vividly portrayed on women’s tombstones.
Blessings over Shabbat Candles
When Shabbat candles are lit, a ritual involving hands takes place. Usually this is done by the woman lighting the candles, though if there is no woman in the house, a man is obligated to do it. The candles are lit, and with both hands she waves the light towards her three times. The symbolism is to draw the spirit of the holiness of the Shabbat towards her. She closes her eyes, covers them with her hands, and recites the blessing. It is this sight of physical movement, bathed in the soft glow of the candles, and the faint murmur of her prayers that has been etched into the memories of so many generations of Jews.
It is often the physical aspect of a ritual that not only adds to but impresses on us the importance of the ritual, so that we remember it long after the ritual is over. That is what Jewish hand signs are all about.