After fighting Albus at the Mystery Manor, Shanoa returns to Ecclesia and is asked to cast the Dominus Glyph Union. Upon doing so, Shanoa dies and the game ends. What did I miss?
You need to rescue all of the villagers.
In order to continue the game beyond the Albus battle, you need to find and rescue all 13 villagers, scattered throughout the various areas in the game. Look at the cutscene after Shanoa casts Dominus--this should hint you toward where the villagers you missed are. Some of them are tricky to find: for example, Irina is hidden behind a breakable wall on the left side of the waterfall at Tristis Pass.