What skills does everyone believe are most important for an auditor to possess? (I'm working on developing a new competency model and wanted to get a baseline from everyone!)

I recently went through a similar excercize consulting for the first line of defence compliance professionals.  I broke the skills into several categories and got with stakeholders for feedback.  There are the technical skills about the business being assessed, soft skills and interpersonal communication, technical skills for auditors, etc. After the categories are complete, I populate the specific skills within each category and rank their importance in the job (i.e., you don't have to be a world class expert in every skill).  To close out, I see the most successful auditors who display intellectual curiosity (always asking why), display grit and tenaciousness to dig deeper while still not getting lost in their main assigned tasks, and of course the interpersonal skill to influence the auditees, as well as their own colleagues.
Once the skills are mapped out and ranked, this can be used to influence training and development activities.  The biggest challenge is the administrative effort to link everything together. I'm sure someone will develop an automated way to meet this challenge in the near future.