Where does “Airéas” come from?

Airéas (Irish) comes from Ancient Greek Ἄρης, from Ancient Greek ἀρή — bane, ruin.

Ancestry of “Airéas”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	Ἄρης	Ares; the planet Mars; {{l\|en\|Ares}}
2	Ancient Greek	ἀρή	bane, ruin