Pugnus Sanctus Dei not appearing after doing requirements

[Kaden95]

As the titles says - did anybody else have issues with this? You have to complete two of the Hidden History discoveries (St. Thomas Corvacho, and the one in Meeker Square) to unlock the weapon. I've done this, and the weapon is nowhere to be found. I've checked both the weapon stash at the Saint's base/tower, and multiple different Friendly Fire stores. It's unfortunate because I noticed this waaaay late into my playthrough, so I may need to start another save and unlock the associated Bonus Round trophy.

 

Hoping someone may be able to offer some sort of fix, but I know it's a long shot!