Here are the conditions for each route:
Goddess Route - Pull out less than seven swords from the Vile God before clearing Cavare Desert - Sanctuary.
Vile God Route - Pull out at least seven swords from the Vile God before clearing Cavare Desert - Sanctuary.
Evil Goddess Route - Pull out at least sixteen swords from the Vile God before clearing Cavare Desert (the first part, not the sanctuary part).