I beat the sun sanctuary level with the Timebender and during it I got the sun stone legendary item from capturing the mini boss (I don't remember what the sun stone was called exactly). After the level when it was doing the score thing it said I found the sun stone thing. Now I can see it next to the Timebender and it says it will replace a symbol on my four dice in the crystal nexus level. I does not seem I can unequip it or put it on a different character. 

Does other level have a legendary item you can unlock or is it only in the  sun sanctuary from the mini boss? Also if I want the sun stone on a different character do you have to get it as the character you want it on? I have only one legendary chests before and was not able to open it, so if that is how you would unlock them and have to do that as all characters that would be a pain to do.

I have had a lot of fun in the game so far, but I wish it explained the legendary items better. Could anyone who knows more about the legendary items explain how they work to me?

I figured it out now. For anyone wondering. The sunstone is the only legendary item that you can unlock for the crystal nexus (at least in the normal levels). You have to unlock it with each character which is fine as it is guaranteed to be there, just get it during getting 5 star with each character.

There is actually a second one, it would pretty unbalanced if only day was represented.