She had planned for many things in that prison. A way to gain many souls and empower herself through a ritual. Maybe one soul capable of entering Valhalla, and an army of einherjar to sic on the remaining humans, and then go after their settlements and bases.
Plans which were mauled and destroyed by the God-Devouring Star and Yraka. However, to see this child who survived, the one who bore the powers and abilities of a famous eastern blacksmith...
It wasn't anywhere in these plans. She thought for her to die. She may have had potential, but it wasn't in the likes of Albert and the others. While surely leagues above Mario, it wasn't at the same level as her best in stock...
One of them even managed to wound the God-Devouring Flame while he had to be mindful of this brat. If not, the chances were that Albert would've become cinders before he could even think.