Not about leadership per-se but The Seven Habits of Highly Sucessful People has a lot of good stuff that would help someone in a leadership role, just make sure you find an older copy thats just by Stephen Covey because his weirdo son has shitted up the more recent editions (in my opinion).

Zen Lessons: The Art of Leadership is mostly quotations and short essays so it can be read in bits and peices here and there. Its more of a philisophical thing and doesn't give concrete instructions or anything.

Not a book recommendation but a generaln rule I was taught a long time ago was "praise in public, chastise in private", with "chastise in private" being the more important part. People generally appreciate it when they've been spared from public humiliation, and they'll be more open to criticism in a more private setting.