Where does “arfbeisiau” come from?

arfbeisiau (Welsh) comes from Welsh arfbais, from Welsh arf, from Middle Welsh arf, from Proto-Brythonic arβ̃, from Latin arma, from Late Latin armistitium, from Latin sistere, from Proto-Indo-European stísteh₂ti — to stand.

Ancestry of “arfbeisiau”, step by step

arfbeisiau traces back through two separate lines of ancestry.

via Welsh arfbais

StepLanguageWordMeaning
1Welsharfbaiscoat of arms
2Welsharfweapon, armament; tool, instrument
3Middle Welsharfweapon, arm
4Proto-Brythonicarβ̃weapon, arm
5Latinarmadefensive arms, armor/armour, shields, weapons of...
6Late Latinarmistitium
7Latinsisteresecond-person singular future passive indicative...
8Proto-Indo-Europeanstísteh₂tito be standing up, to be getting up
9Proto-Indo-Europeansteh₂-to stand

via Welsh Iau

StepLanguageWordMeaning
1WelshIauJupiter, Thursday
2Middle Welshieu
3Brythonic*Yow
4LatinIovem
5Proto-Indo-Europeandyew-to be bright; sky, heaven
Every word from Proto-Indo-European steh₂-