Green’s Dictionary of Slang

(US) weak, ineffectual.

2003		A. Bahal excerpt from Bunker 13 in USA Today 21 May 🌐 He thinks of guys like you as soft ass to regulate, show what a tough guy he is.
2011		W. Henderson City of Nightmares pt 2 109: When he would complain about us fucken him up too much, we would say, ‘this roughhouse you soft ass nigger. You can't take it’.
2021		S.A. Crosby Razorblade Tears 63: ‘[P]eople out here thinking we soft-ass punks’.