Taking the cake for worst Leadership attachment in my books is the catastrophe that is Diligent Noble. Noble is the single-most common trait, making this card a tough sell from the get-go. However there is then almost zero synergy around the trait. The one card being drawn makes this card probably better than others down here when being forced to play it, but the fact that there are so many better options for draw out there makes this (in my humble opinion) the leadership attachment least likely to ever make a deck.
Rating: 0.5/10
Decks of mine using Diligent Noble