Here is a list of secret weapons, i'll give the best source of finding them.

AER14 Prototype - It's a laser rifle that shoots green, Dps = 69 Dam = 19 Str 3 Wg 8.50 It takes MF Cells (Location is somewhere in a vault the one with like spore creatures or something)

Annabelle - It's a rocket launcher of some sort Dps = 16 Dam = 73 Wg = 15.00 Str = 5 It takes Missile's (Location = I have no Idea I found it somewhere in a shack)

Euclid's C-Finder - Im not really sure, it looks sorta like the alien blaster from f3 Dam = 0 Dps = 0 Wg 15.00 Str 1 And takes ARCHII Charge (Location is from the one kid chasing the girl in freeside)

Love and Hate - Is a Spiked Knuckles, Dps = 52 Dam = 33 Wg = 1 Str = 3 (Location is from a fiend somewhere)

Nephi's Golf Driver - is a 9 iron Dps = 52 Dam = 24 Wg = 1.00 Str = 2 (Can be found by killing Nephi AKA A fiend)

Q-35 Matter Modulator - Dps = 95 Dam = 27 Wg = 6.00 Str = 2 Takes MF Cells (I forgot location)

Tesla-Beaton Prototype - Dps = 126 Dam = 69 Wg = 8.00 Str = 8 Takes EC Packs (I forgot location)

Well, there we go I found all of these by exploring and, so i thought I would share but Idk if the Annabelle is one so I just posted it but Yw