There's a little over 100 accessories in the game, many of which you find as the game progresses. It's advised that you don't sell any of them, because some of them you need to evolve into later items, and cannot find or buy again if you sell them. So here's a list you can use as a checklist or reference. If you have possessed at one time or another each of these items, then you qualify for the Item Hunter trophy.
Bangles increase your HP a set value. Iron Bangle, Silver Bangle, Tungsten Bangle, Titanium Bangle (commonly missed), Gold Bangle, Mithril Bangle, Platinum Bangle, Diamond Bangle, Adaman Bangle, Wurtzite Bangle.
Wristbands increase your attack power. Power Wristband, Brawler's Wristband, Warrior's Wristband, Power Glove, Kaiser Knuckle.
Marks increase your magic attack. Magician's Mark, Shaman's Mark, Sorcerer's Mark, Weirding Glyph, Magistral Crest.
Belts increase physical resistance. Black Belt, General's Belt, Champion's Belt.
Braces increase magical resistance. Rune Brace, Witch's Brace, Magus's Brace.
Armlets increase both resistances. Royal Armlet, Imperial Armlet.
Elemental rings increase elemental resistances. Fire: Ember Ring, Blazefire Ring, Salamandrine Ring. Ice: Frost Ring, Icicle Ring, Boreal Ring. Thunder: Spark Ring, Fulmen Ring, Raijin Ring. Water: Aqua Ring, Riptide Ring, Nereid Stream Ring. Wind: Zephyr Ring, Gale Ring, Sylphid Ring. Earth: Clay Ring, Siltstone Ring, Gaian Ring.
Status Items increase status effect resistances. Debrave: Giant's Glove, Warlord's Glove. Defaith: Glass Buckle, Tektite Buckle. Deprotect: Metal Armband, Ceramic Armband. Deshell: Serenity Sachet, Safeguard Sachet. Slow: Glass Orb, Dragonfly Orb. Poison: Star Pendant, Starfall Pendant. Imperil: Pearl Necklace, Gemstone Necklace. Curse: Warding Talisman, Hexbane Talisman. Pain: Pain Dampener, Pain Deflector. Fog: White Cape, Effulgent Cape. Daze: Rainbow Anklet, Moonbow Anklet. Death: Cherub's Crown, Seraph's Crown.
Critical items have effects that trigger when HP is low, once per battle. Guardian Amulet, Auric Amulet, Watchman's Amulet, Heroes Amulet, Saint's Amulet, Zealot's Amulet, Flamebane Brooch, Frostbane Brooch, Sparkbane Brooch, Aquabane Brooch, Herme's Sandals, Tetratic Crown.
Auto items are evolved forms of Critical items and have you start a battle with that effect. This order is the same as the above section, for what evolves into what. Shield Talisman, Soulfront Talisman, Shrouding Talisman, Morale Talisman, Blessed Talisman, Battle Talisman, Flameshield Earring, Frostshield Earring, Sparkshield Earring, Aquashield Earring, Sprint Shoes, Tetratic Tiara.
Charms have a random chance to absorb an element and can only be found on the surface of Gran Pulse in chests. Fire Charm, Ice Charm, Lightning Charm, Water Charm, Wind Charm, Earth Charm.
Other items have specific effects with abilities that don't fall into other categories. Doctor's Code, Whistlewind Scarf, Aurora Scarf, Nimbletoe Boots, Twenty-Sided Dice, Gold Watch, Winner's Medal, Survivalist Catalog, Collector Catalog, Connoisseur's Catalog, Hunter's Friend, Speed Sash, Energy Sash, Entite Ring, Goddess's Favor, Ribbon, Super Ribbon, Genji Gauntlet, Growth Egg.