Bad if it's in the wrong hand, they can cause a great disaster if they get it's power.
Because it can create a dragon lord, all dragons can be more coordinated. This can cause issues since dragons by themselves were already dangerous but having multiple is a world threat. That is probably the reason as why the dragons lost the war. Their ego's to not work together made them lose.
And Rurin, the little dragon, the reason she was scared/traumatized is what we have read and seen what I assume is that her kin had killed her mother for the orb which may be the real reason as to why she is cold towards other dragons, and seeing that orb resurface her past memories.
I think her mother was dragon lord
And she remembered how her mother died that's why she was scared
Why is the orb a bad thing? Why was the little dragon so scared?