After suffering for a while I figured out a rather crude solution to the problem, editing the Coalesced.bin file to fix a hotkey to spawn the weapon.
It worked perfectly.
This is how you do it:
I’ve been stuck for quite some time for this bug, barring me from finishing Mass Effect 3. Then I remembered about the trick which I used to access all weapons, DLC and/or otherwise, by editing the Coalesced.bin file which actually is a compiled collection of multiple INI files.
What you’ll require is Wenchy’s Coalesced Editor, which is way better than that of Gibbed (who is good for the savegame editor though …) and a functional brain with a sane mind.
If you seem to have the above stated at your disposal then please proceed to the next steps by first backing up your original Coalesced.bin file.
Open the Coalesced Editor and then proceed to opening the Coalesced.bin file which is located in :\\BIOGame\CookedPCConsole.
Then, from the left treelike menu, choose “bioinput.ini”, then “sfxgame”after that “sfxgamemodedefault”. The following screenshot would be helpful for you to identify the entries which are boxed in red for your convenience.
In the right-hand side you’ll see the list from the Bindings section which shows how the key-bindings are defined for the game controls.
In the end of the list add the following line: ( Name=”F12″, Command=”giveitem self Cain” )
Save the changes in the Coalesced.bin file and start the game.
Then while in game, press F12 to access the M-920 Cain to take down the Hades Cannon and move on to your next objective!