From
The Origin of Hoagies, Grinders, Subs, Heroes, and Spuckies
But the weirdest-sounding of all has to be "wedge," which is only familiar to natives of Westchester County, NY, and Fairfield County, CT, the two counties directly north of New York City. Some sources group it in with the shape-names, based on a diagonal cut in the middle of the sandwich, or a wedge cut out of the top half to make more room for fillings, but the real story's probably the simplest on this list: "wedge" is just short for "sandwich," and comes from a Yonkers deli whose Italian owner got tired of saying the whole word.
I remember when I first encountered Subway, their stores used a wedge cut and I didn't understand why they didn't call
those wedges.