I am in Normal difficulty, I almost finished all quests but I didn鈥檛 find any item to put there. What kind of item you can put there?? Silly question, I know. 
Attachment: 围蠅蟻委蟼 蟿委蟿位慰.jpg
Relics. They can crafted at the blacksmith.
Thanks! I will try it right now! 
The only one you can find (from my knowledge at least) in the game is from a Quest Reward. It ain鈥檛 bad and can be used by most character at low level.
There is a quest when you get to Arkovian and meet the first Rovers (before the Dynamite) where you need to find their Elders. If you lie to them about the old guy stuff saying you didn鈥檛 find anything you will lose on the Rovers reputation but you will get a relic. Normal is level 18 Elite is level 35 and Ultimate is level 50. It offer a boost in stat and an active skill that give you 100% All damage and lot of mana regen for a short period of time (I think 12 seconds). Not great but better than having nothing in there till level 70 like my first character did!