Humility, obviously, is foundational:
8Let him recognize that his goal must be profit for the monks, not preeminence for himself.Mercy is another key trait, especially in dealing with disciplinary issues:
10He should always "let mercy triumph over judgment" (Jas 2:13) so that he too might win mercy...15Let him strive to be loved rather than feared.That might be one of the best leadership and management mottoes from The Rule: In a leadership role, strive to be loved rather than feared.
As far as traits to be avoiding in selecting leaders, Benedict offers up this list:
16Excitable, anxious, extreme, obstinate, jealous or oversuspicious he must not be. Such a man is never at rest.