Here is the full list of all 38 Demon's Souls trophies - there are 27 bronze, 5 silver, 5 gold and 1 platinum.
All Trophies Obtained
All Rings Obtained
Obtained Best Weapon by Greystone
Obtained Best Weapon by Darkmoonstone
Obtained Best Weapon by Clearstone
Obtained Best Weapon by Cloudstone
Obtained Best Weapon by Suckerstone
All Unique Weapons Obtained
Obtained Best Weapon by Bladestone
Obtained Best Weapon by Mercurystone
Obtained Best Weapon by Moonlightstone
Obtained Best Weapon by Dragonstone
Obtained Best Weapon by Marrowstone
Obtained Best Weapon by Faintstone
All Spells Learned
Old One Put to Sleep & World United
Obtained Best Weapon by Sharpstone
Slayer of Demon “False King”
Conqueror of Old King Doran
Slayer of Demon “Blue Flying Dragon”
Obtained Best Bow by Spiderstone
All Miracles Learned
Slayer of Demon “Storm King”
Slayer of Demon “Old Hero”
Slayer of Demon “Maiden Astraea”
Slayer of Demon “Dirty Colossus”
Slayer of Demon “Old Monk”
Slayer of Demon “Maneater”
Slayer of Demon “Fool's Idol”
Slayer of Demon “Penetrator”
Slayer of Demon “Leechmonger”
Obtained Best Weapon by Hardstone
Slayer of Demon “Dragon God”
Slayer of Demon “Flamelurker”
Slayer of Demon “Armor Spider”
Slayer of Demon “Adjudicator”
Slayer of Demon “Tower Knight”
Slayer of Demon “Phalanx”