Spectral Souls

Out of curiosity, did you hack the weapons into the game? If so, it may be that the game's usual triggers for revealing them on the weapons reference list (when you buy, synth, find, steal or otherwise acquire them) was bypassed.

Try equipping and unequipping some of them, see if they show up. If not, you may actually have to manually synth or find copies for them to show up on the reference list.

I've got weapons that don't show up in the synth list. Somebody said that they've got the entire list filled in after they cleared OG 50 in a True Ending run - mine didn't do that. Unfortunately, there's a lot we don't know about this game.

Try finishing the game, the game tends to relocate most of items