Sword of Mana/Scaly Lair

Leave the Vinquette Vicinity by heading south three times (there's a silver Mana Goddess enroute here and a pot to plant a Hothouse), then go north-east and north-west.

Head north and open the chest here for an Angel Grail. Return to the previous screen and head south-east, north west, west, go up and follow the ramps around and head straight up to the cave and enter.