In a book edited by John Haldon (A Social History of Byzantium), Liz James writes about the activities of Eirene, an eighth-century empress of Byzantium:
"Wallace-Hadrill saw queens as honorary men because of their links to power, authority, prestige, and honor. In response, Stafford argued that queens did not become men because the title 'king' was reserved for men alone. To suggest otherwise would be to suggest that the title 'king' could be separated from the person of the king and thus filled by either sex. Thus the public body of the ruling queen was not a king's body but a queen's, gendered feminine not masculine. The case of Eirene supports this view. The only evidence for Eirene using the male title BASILEUS is limited to her signature as 'emperor of the Romans' on a couple of legal documents and the use of BASILEUS on one gold coin from Sicily. If Eirene needed to construct herself as a man, as a BASILEUS,then one might expect this title to feature on all of her official documentation, on all coins and seals. Instead, she used the feminine form, BASILISSA, which was also the title which Byzantine historians of her reign use for her."
The Sicilian coins are not easy to read because the lettering is obscured.
See p. 45-46 of the this book.