The holy sword is available on the first level of Iona's dungeon (slightly west of centre, in the northern part of the first level). Take the graveyard entrance back in, and look for a pentagram on the ground with a lit candle...
Gathering the Holy Items and the SacrificeIn the eastern part of the graveyard (where you got the Shrimpo quest), a little to the north, there is a rough ring of gravestones with the names and occupations of seven people; read in the correct order, the first letter of each name spells out 'Shrimpo' (IIRC start with a north west gravestone, and read them in a clockwise direction, or something like that).
Silver Armour and Treasure Maps