At this time, most of the items you find from your battles will be armor, weapons, jewelry, and sometimes enhancement stones or hero cards (from defeating bosses).
Armor, weapon, and jewelry items come in different grades. Different colors for the borders assist in quickly identifying their quality, which are described as follows:
Grey: Also known as "Normal", these items are the lowest grade you can get and are therefore quite common. Try to replace them with better items as soon as possible.
Yellow/Gold: Also known as "Uncommon". These are definitely better than "Normal" grade items and would be a good start for upgrading through enhancement. Yellow/Gold color and above are primarily found through unlocking sealed items with "Premium Keys", as described below.
Green: Also known as "Rare". These are just that, quite rare. You will probably not want to sell these items as they aer hard to find. Even if one of your heroes "outgrows" one of your green "rares", you may wish to keep it around for another lower level hero that you may level up one day. A prime choice for enhancing!
There are rumors of even better grade items, so keep your eyes open for them! Acquiring one would be quite a feat indeed!
Sealed Items: Sometimes you will loot items which have a "?" over them. On closer inspection you will notice it is "sealed". This is an item that you need to identify first. To do so, you'll need to use a key.
Keys are consumable and there are two different types, "General Key", and "Premium Key". Both are available in the store for purchase, or you can win a few of them through event rewards. General keys only yield standard grey normal items, whereas Premium keys will unlock the higher grade items.
More to be added later!