Thanks for pointing me in the direction of that gamefaqs thread. Here is a list of everything that is known at the moment. You can unlock some pretty sweet stuff in this game! A lot of these look like they will be good side goals to shoot for when grinding. Apparently there is also a way to unlock new character models, like female models, demons, birdmen, and so forth.
Head Items -
Crown: collect 500 cards
ninja mask: achieve victory with out paying a single toll
Pirate Hat: receive 20 tolls or more, achieve victory
jester hood: Exhaust the opponent through tolls, achieve victory
Leather Helm: pay 400 G or more in a single toll and achieve victory
Valkyria Helm: Achieve victory (other than sudden death) when opponent(s) hold no land
Chain Helm: Fail five or more invasions
Dwarven Helm = Achieve Victory after Chaining 10 or more territories
Snake Circlet = Achieve Victory using a book containing only neutral creature
Cowboy hat : receive 3000G or more in a single toll
Chain Helm: fail 5 or more invasions
Mummy Mask = Achieve Victory having obtained a total magic of at least 90,000
Lions Helm: 200 HP or more creature and win (?)
Brave Helmet: 200 ST or more creature and win (?)
Plate Helm : Achieve victory without fighting once
Wizard Hat : achieve victory using a book containing no creature cards
Storm Causer : Destroy 10 or more creatures at once. Achieve victory.
Goat Helm : Using a book of only R-rarity cards obtain a total magic of at least 10,000
Shogun Helm - Pay a total of 3000g or more in tolls. Achieve victory.
Body Items -
Gladiator Mail: Complete "Santana Village" in story mode
Leather armor: Pay 5 or more toll and win
soldier armor: compete Alcyon the imperial capital in story mode
Chain Mail: lose 5 or more lands. Achieve victory.
Storm armor : change all squares to air and water element and win
Magma Armor : change all lands to fire and earth elements
Training Coat : Complete "The Anchoress' Mansion on Mt. Etumer"
Dwarven armor = Raise to level 5 at least one territory for each of the four elements and achieve victory
ninja armor - win a 2v2 with your ally never paying a toll
Cepter Robe : Complete " Provedin, Palace of the Sun" story mode
Shining Robe : Complete " The Altar of Light" in story mode
Darkness Robe : Complete " The Altar of Darkness" in story mode
Jester Armor- Exhaust Magic and still achieve victory.
Snake Armor : Achieve victory using a book containing no more than 1 of any individual card.
Plate Mail - Pay 20 or more tolls. Achieve victory.
Back Items -
Red Champions Cloak: Beat the Colosseum III level in story mode
Water Cloak = Using a book containing only water creatures, obtain a total magic of 10,000 or more against a story mode opponent, and achieve victory. (just a note, the actual condition says to do it in story mode, but I just obtained it in Versus mode)
Air cloak : a book using all air creatures with a goal of 10,000 or more win
Fire Cloak : 10,000 goal win with only fire creatures in your deck.
Neutral cloak : Collect all the Neutral creature cards except E cards
Angel Wings = On a map with no temples obtain 3,000G or more using symbols and achieve victory
Black Cat's Tail (Back): Use a book containing only N-rarity cards, obtain a total of 10,000G or more in story mode and achieve victory.
Squirrine Tail : Using a book containing only S-rarity cards obtain a total magic of 10,000G or more.
Devil Wings: Achieve victory without owning territories and without using a single symbol
Hand Items -
Mace: Receive 5 or more tolls and achieve victory
Buckler: Defend land from enemies 5 or more times and win
Claymore: Steal land from enemies 5 or more times and win
blade of culdra: get 1000 cards
magic shield: Achieve victory without using spell cards
Prismatic Wand: collect all item cards except E cards
holder blade: compete Alcyon the imperial capital in story mode
fire shield: collect all fire cards except E cards
Tower shield: Achieve victory by collecting over 1000G from tolls and have 0 items in your deck
Water Shield : Get all water creatures except for E cards. (also get a free ecard)
Air Shield : get all Air creatures but E cards. (You get a free e card with this one)
Earth shield : get all Earth creatures except for E cards
Wizard Staff : Collect all spell cards except for E cards
Knight Shield = defend land from the enemy 20 times or more and achieve victory.
Trident - Achieve victory within 20 rounds other than by sudden death