How would you blazon this?

[King John]

Take a look at the escutcheon in this picture, and tell me how you'd blazon it?

I thought of Per fess gules and gyronny sable and azure ..., but if I saw that blazon, I'd draw the gyrons all meeting at the middle of the base half of the shield. So ... how?

— Blanc Wolf Herald

[Sir C. M. Siervicül]

I was wondering this myself in trying to figure out how the state flag of Arizona would be blazoned. I can think of two possibilities for the base half - "gyronny from fess point sable and azure" or "gyronny sable and azure issuant from the line of division." Not great but that's the best I can find.