Drawing by Avanzino Nucci (1551-1629) ...

I once bought this pen and white drawing on bluish paper, diam. 21,0 cm, at an auction. On the avers is Cesar giving a fiery speech to his soldiers. In handwritten Renaissance Italian: 'Cesare i suoi soneras ponito accen ...'. The rest of the text is lost. Too small to make a good photo of it. On the revers part of a male figure. The company didn't know anything about the drawing, so I showed it to two museums. They agreed on Italy, Rome, late 16th century and Avanzino Nucci (1551-1629) as the most probable artist. He often wrote text on his drawings and it looks like his handwriting. But they differed about the purpose of the drawing. In the first museum they believed it's a suggestion for decoration on the occasion of the jubilee year 1600. In the second museum they believed it's a suggestion for a maiolica plate. Maybe you know better ?