Green’s Dictionary of Slang

1. (US Und./W.I./UK black teen) a high- or top-ranking villain.

1914		Ogden Standard (UT) 7 Mar. 12/2: Haynes is credited, in his craft, with being about the ‘high notch’.
1998		Fatal ‘Time’s Wastin’’ 🎵 on In The Line Of Fire [album] I’m wearin’ the teflon vest / rest in born in rubbish, free spots, and Ez spots / rock like Holly Mzots, one of the top notches of the block.

2. a first rate or very attractive individual.

2003

posting at Urban Dict. 2 June 🌐 He’s to [sic] young, but he’s going to be a notch when he gets older.