Where does “Grischa” come from?

Grischa (English) comes from Russian Гриша, from Russian Григо́рий, from Ancient Greek Γρηγόριος, from Ancient Greek -ῐος, from Proto-Indo-European -yós — Creates adjectives from noun or verb stems.

Ancestry of “Grischa”, step by step

Step	Language	Word	Meaning
1	Russian	Гриша	—
2	Russian	Григо́рий	Gregory
3	Ancient Greek	Γρηγόριος	watchful, vigilant
4	Ancient Greek	-ῐος	belonging to; of”, “belonging to”, “pertaining to
5	Proto-Indo-European	-yós	Creates adjectives from noun or verb stems

Every word from Proto-Indo-European -yós →Every word from Ancient Greek -ῐος →Every word from Ancient Greek Γρηγόριος →