My guess is Dux and Santos would provide some proper info but this is the best way I can put it:
a fight takes place between two or more parts, it is an interaction, in which both prey and defence are involved, I truly believe you need both to build up drive. as far as dogs go, I believe you see that in how much the dog actually DESIRES to carry the fight, not just do it because it has to defend itself etc. Also I believe fight drive in a dog always comes with self-confidence and the signs to look for it would be the "classic" ones.. tail up, in fact pretty much everything is "vertical" when in a fight mood, in my own opinion. In my experience, the signs that always led to fight dominance were tail up, upright hair on the spine, low pitched growl and forward positioning of the body, no fear in taking the fight to the opponent.
getting back to the self-confidence bit - I believe a dog with good fight instinct shows good self confidence in general, not just in a state of conflict.
Banuiesc ca Dux si Santos vor oferi niste info de calitate dar asta e raspunsul cel mai bun pe care eu personal il pot da:
o lupta se duce intre 2 sau mai multe parti, este o interactiune, in care atat atacul cat si apararea sunt implicate, sincer cred ca e nevoie de amandoua pt a obtine pe cel de lupta. In privinta cainilor, cred ca poti "vedea" instinctul de lupta prin prisma DORINTEI manifestate de caine, de a duce lupta, nu doar sa lupte pt ca nu are de ales, trebuie sa se apere etc. Mai cred ca instinctul de lupta vine automat cu increderea de sine iar semnele prezentei inst. de lupta sunt cele "clasice", in opinia mea, coada ridicata,.. de fapt mai toate sunt "verticale" cand esti 'setat" pt lupta. Din ce am vazut pana in prezent, cainii cu instinct puternic de lupta pe care i-am notat aveau urmatoarele semne, coada sus, parul pe spate / ceafa ridicat/zburlit, marait gros si o postura de "inaintare", un fel de semn ca nu se teme de conflict, nu se teme sa duca lupta la adversar.
Legat de increderea de sine - cred ca un caine cu instinct bun de lupta arata incredere de sine in general, nu doar in situatii de conflict.