For now and until we get more info, I'm gonna call that woman The Queen of King Gaiseric.
She is branded AND whoever branded her (We have ear an story about a sage in the tower of conviction who called to god and his angels answered destroying Gaiseric's capital, most probably Void was that sage) also branded the land (see background in page 16) and we have seen all the corpses branded in the buried city of midland, this somehow parallel the eclipse when Griffith becomes Femto, (Void offers the ones he loves, citizens and royals of the kingdom, Griffith offers the Falcons ) and the incarnation of Femto after Egg apostle offered and branded the land.
Problem I see right now is, when Gaiseric got the berserk armor?
He is donning the berserk armor in this flash back, so, he got it before the eclipse were Void ascend to the god hand?
or
Gaiseric survived like Gutts the ascension of Void and this flashback is the moment when SK lose his last bonds to humanity (what will happen if Gutts lose Caska and his currents companions) and the berserk armor consumes his body only letting left SK spiritual body? maybe this as parallel of the events of Femto incarnation with the difference Caska survived but Queen not?