Green’s Dictionary of Slang

(US) a truculent, short-tempered person or animal.

1850		L.W. Garrard Wah-to-yah and the Taos Trail 64: In our lodge were three huge curs and four cross feists.
1913		H. Kephart Our Southern Highlanders (1922) 94: You know a feist is one o’ them little bitty dogs that ginerally runs on three legs and pretends a whole lot.
1949		W.R. Burnett Asphalt Jungle in Four Novels (1984) 135: A big-mouthed, silly little feist.