If you just explore everywhere you should find the holy items (dagger, sword and amulet). There is one in Verdistis, one in the Dark Forest, and one in Rivertown (that you can reach after going to the castle, which incidentally, you do not need to rush). The item's description will say the '2 must be sacrificed...' line, so it is hard to miss them.


Gathering the Holy Items and the Sacrifice

VERY BIG SPOILER ON HOLY ITEMS - some links to screenshots are broken