In Eastern Europe, it was very common to name children with Yiddish names, which were very often a variation of an originally Hebrew name. "Pessy" is one such name.
According to the sources I've seen, "Pesse" is a Yiddish form of "Batya," which in Hebrew means "daughter of G‑d."
According to tradition, Batya was the name assumed by the daughter of Pharaoh (the one who rescued and raised Moses) after she converted to Judaism.
I hope that I have been of help.
Wishing you much success,
Rabbi Baruch S. Davidson