@NickTheodorov,
German "Nagel is the same as English 'nail' ('nog' is a new word, first used in 1693)
German "Flegel" > Middle English fleil, flail, partly from Old English *flegel (whence Old English fligel), from Late Latin flagellum flail, from Latin, whip & partly from Anglo-French flael, from Late Latin flagellum
'sag' is related to German "sacken" (to sink)