Since we can't do your essay for you, you have to decide what the best quality of a historian is <em>to you.
But, </em>I can give you a good starting point!
Some good qualities can be -
<em>* thorough </em><em>* scientific and critical evaluation </em><em>* immense education </em><em>* enthusiastic </em><em>* a good team worker </em> Hopefully, this helps you! =)
I think a historian has to be curious to be successful. This is simply because if a historian does not have a drive to learn more information\, they will not try. However, if they keep the child-like mindset of always needing to know, they can go far with their discoveries and studies.