An Etymological Dictionary of the German Language/Annotated/Weise
Weise, feminine, ‘manner, mode, way,’ from Middle High German wîse, Old High German wîsa, feminine, ‘method’; corresponding to the equivalent Anglo-Saxon wîse, English wise, Dutch wijze, Old Saxon wîsa. From this West Teutonic word (in Old Icelandic vísa) the equivalent Romance cognates, Italian guisa, French guise, are derived. Teutonic wîsô-n- seems, like weise, to be derived from the Teutonic root wī̆t, ‘to know’; hence Weise, literally ‘knowledge’?. See Art. — The suffix -weise (e.g., in teilweise) has been developed in Modern High German in connection with Middle High German phrases, such as in rëgenes wîs, ‘like rain.’