[1] He worked for a short time from 1932 to 1933 in the Department of Western Manuscripts of the Bodleian Library, and obtained his D.Phil from Oxford in 1934, in the same year winning the Charles Oldham prize.

[5][7] He also met the novelist Barbara Pym, who later used him as the basis for the character Count Ricardo Bianco in her first novel, Some Tame Gazelle (1950), which she had begun writing while at Oxford.

[4] Other than his period of military service, Weiss taught at University College, London from 1938 until his death.

[11] A reviewer from its first publication said that "young Weiss's meticulous scholarship had already long been recognised",[12] and it was elsewhere described as "the best general guide" to its subject,[13] and as the work in whose shadow other scholars remained seven decades later.

[5] He stated that he could have turned each of the last ten chapters of The Renaissance Discovery of Classical Antiquity into its own book.

[5] His obituary in the medievalist journal Speculum called him "one of the most learned and productive scholars of his generation".