Hi,
how do I use items like Mana Emerald or trinkets in a fightclass?
Using them by name like a spell seems not to work

Hello, there is many ways to do what you are asking, C# and lua.

Take your pick of one that works for you.

1st :
string ItemName = ItemsManager.GetNameById(50259);
Lua.LuaDoString("UseItemByName('" + ItemName+ "')");

2nd :
ItemsManager.UseItemByNameOrId("50259");

3rd:
ItemsManager.UseItem(555);

4th : 
ItemsManager.UseContainerItem("Name here");

5th : 
Lua.LuaDoString("UseItemByName('ItemName Here')");