Hmm... IMDb says he played a hospital assistant in APOCALYPSE DOMANI and Fazi henchman in IL CINICO, L'INFAME, IL VIOLENTO but I am not so sure if this is correct. Look at these pictures:
Fazi henchman in IL CINICO...
Hospital assistant in APOCALYPSE DOMANI:
This is Renzo Pevarello - not Ettore Arena. Maybe someone thought Pevarello as Arena and submitted this info on the IMDb??