So are you saying Saint Joan of Arc is suffering eternal damnation in Hell?
St. Joan wasn't excommunicated; she received holy Communion before her execution. In any case, her trial was manifestly unjust and illegal (her appeal to the Pope was ignored), and hence a sentence of excommunication would have been invalid. Moreover, unjust excommunications, while they separate a man from the communion of the Church, do not result in damnation, for "the person [unjustly] excommunicated should humbly submit (which will be credited to him as a merit) [. . .] if he submit humbly, the merit of his humility will compensate him for the harm of excommunication" (St. Thomas, Sup., q. 21 a. 4).