I am preparing the dinner fpor this famous night, so not much time to analyze historical references of this family .. The Grand father, Tancred of Hauteville in Normandy has many sons , many of them went to conquest Italy, founding dinasties their with various coats of arms.
A Bohemond received the principality of Taranto from the duchy of Apulia, whose coat of arms is a red lion on a yellow background, different from that Blue and white/red coat of arms of the Kingdom of Sicily, another brother... The young Tancred who went to the Cruzades with Bohemond was a side nepheww, but Wikipedia does not cite the branch of the family, therefore the shield content.
I woukd personnally use the blazon of the de Hauteville family, in absence of date, or seach deeper in various sources, bu no time for me today. The dragon on the illustration looks perhaps funny.
More search should be done on the grand sun Tancred who went to Jerusalem, to find out, but unsure at this stage.... Sorry...