The pianist in question can only be the famous Paul Wittgenstein
(November 5, 1887 - March 3, 1961).  He was from a distinguished and
well-known Viennese family; his younger brother was the philosopher
Ludwig Wittgenstein.  They grew up in the centre of the cultural milieu
of pre-1914 Vienna and knew Mahler and Richard Strauss amongst other
notable figures of the time.

Paul Wittgenstein was a pupil of Leschetizsky and was just beginning
to embark on a promising pianistic career when war broke out and he
was called up for service in the Austro-Hungarian army.  Unfortunately,
he became a casualty of the conflict as he was shot in the elbow and
his arm had to be amputated, then he was captured by the Russians and
ended up as a prisoner of war in Siberia.  However, after the conflict
he was determined to overcome his disability and learnt to play the
piano using just his left hand.

He went about rearranging suitable piano pieces and commissioned
works from various composers, most notably Strauss, Prokofiev,
Hindemith, Britten and Ravel.  The latter composed for him the famous
and well-known "Concerto in D for the Left Hand", a masterpiece which
remains the only work he commissioned which survives in the standard
concert repertoire.

A recording of him playing this concerto is to be found on YouTube,
an interesting document.  Wittgenstein plays with a somewhat imperfect
flourish, but Ravel apparently was none too pleased about some passages
which Wittgenstein thought he would 'improve'.

In my Hupfeld catalogue from the 1920s there is only one roll listed
under Wittgenstein, a late issue 58793, Chopin's Etude Op. 10 No. 2.

Having never encountered this roll, I always wondered if this was
Chopin's original made before WW1 or an arrangement by Wittgenstein for
the left hand.  Clearly it's the latter and it would be interesting to
hear.  Evidently he had at least one recording session at the Hupfeld
studios, but would surely not have merely recorded one short Chopin
study, so I would guess the session included other left hand arrangements
or compositions which were not issued.  Or maybe they were?

Much more about Paul Wittgenstein can be found on Wikipedia.  And a
huge thanks to Marc Widuch for making these 'faszinating' photographs
and records widely accessible.

Best regards,
Paul Tuck
London