So narratively, a fighter with this feat/skill/what-have-you, never, ever misses?
Halivar and I are on the same page here.If I was rolling a fighter with this ability, I would perhaps describe it as a fighter who knows how to force an opponent into an awful option; to take a hit or sacrifice footing (or giving him some other disadvantage that can be agreed with the DM as falling within the purview of the hp abstraction, and not otherwise modeled elsewhere in the rules).
And as for "never, ever missing"? Not at all: just being able to reliably where down an opponent at least a little bit every 6 seconds of melee. (Ie it's only "never misses" if you assume that there is only one attempt to hit per 6 seconds - which seems pretty un-verisimilitudinous to me!)