‘St. Magnentia (2), Nov. 26. Represented with St. Germain d’ Auxerre. She accompanied his relics when they were brought back from Ravenna : none of her companions in this pious office seem to be represented with him. Magnentia died at Ste. Magnence near Avallon. AA.SS. Cahier.’
The Bollandists (AASS, Acta Sanctorum) mention her with lots of footnotes in the entry for St Germain of Auxerre, but there is no further detail that I can make out. However, M Lopez Ginisty obliges with another troparion:
Ton 4 Tropaire à sainte Magnence, vierge, (Natalice en 448 A.D.)
Avec quatre de tes compagnes tu allas*
Chercher les reliques de saint Germain d’Auxerre*
Pour les ramener dans sa ville épiscopale.*
Myrrhophore bienheureuse du saint prélat,*
Sainte Magnence, intercède auprès du Seigneur,*
Afin qu’Il nous accorde Sa grande mercy!
With four of your companions you went
To seek the relics of St Germain of Auxerre
To restore them to his episcopal city.
Fortunate myrrh-bearer of the holy prelate,
St Magnentia, intercede before the Lord,
That He grant us his great mercy!