Of all the histories of weapons/systems I’ve read, over hundreds of years, there seem to be only a few variants

I. The weapon is adopted due to the personal support, possibly corrupt, of an influential patron AND

A) it is a revolutionary advance
B) it is an advance, but too expensive to justify
C) it is suited to a theoretical situation or tactics that never arise

II. The weapon is adopted after extensive testing incorporating multiple variables AND

D) it is a solid workhorse
E) it is widely reviled as shit by users (tho maybe not quartermasters)
F) it completely fails under battlefield conditions and requires multiple revisions

Might get this from a poor sample, do pass on your favorite exceptions. I would expect to run into I.F more often, but given that cost tracks complexity maybe that bottlenecks on B first