Doctor Dionysius Genoni's plan to scare the protagonist involves dressing characters up and placing them in picture frames, and the protagonist stabs his rival Tito Belcredi at this work's end; that man had earlier caused the protagonist's debilitating accident.  
One character reveals that she caused the titular character's condition when she started going by "Matilda," and that character's daughter Frida is now engaged to his nephew.  Doctor Dionysius Genoni's plan to scare the protagonist involves dressing characters up and placing them in picture frames, and the protagonist stabs his rival Tito Belcredi at this work's end; that man had earlier caused the protagonist's debilitating accident.  In this work, Count Charles di Nolli hires Harold, Landolph, Ordulph, and Berthold to act out the drama that occurred during 1077 at Canossa.  FTP, name this play whose title character believes he is a Holy Roman emperor, a work of Luigi Pirandello.
One character reveals that she caused the titular character's condition when she started going by "Matilda," and that character's daughter Frida is now engaged to his nephew.  
{Enrico IV} or {Henry IV} (5) [AH]