Where does “Kaðrina” come from?

Kaðrina (Old Norse) comes from Old Norse Katrina, from Ancient Greek Αἰκατερίνη, from Ancient Greek Ἑκάτη, from Ancient Greek ἑκάς, from Ancient Greek ἕ, from Proto-Hellenic hwe, from Proto-Indo-European swé — self.

Ancestry of “Kaðrina”, step by step

Step	Language	Word	Meaning
1	Old Norse	Katrina	—
2	Ancient Greek	Αἰκατερίνη	—
3	Ancient Greek	Ἑκάτη	Hecate
4	Ancient Greek	ἑκάς	afar, far off; long after
5	Ancient Greek	ἕ	him
6	Proto-Hellenic	hwe	—
7	Proto-Indo-European	swé	self

Every word from Proto-Indo-European swé →Every word from Proto-Hellenic hwe →Every word from Ancient Greek ἕ →