What follows is observational, based on 20+ years recruiting for corporate law departments.  In my opinion, here are the Top 5 traits needed to become a great General Counsel:

1. Calm Confidence.  You have heard the term "Boardroom Presence" as a pre-requisite for success in the C-suite, and this certainly applies to the general counsel.  Great GCs show boardroom presence daily and not just four times per year.  They are calm, consistent, and confident.  The term "never let them see you sweat" should be part of every general counsel job description.  While you can be human (see #2 and #4 on this list), emotional outbursts, wavering, or negativity of any kind are to be strictly avoided.