EDIT: CORRECTION this secret is for those of you who use EVE (which I'm assuming is quite a lot of you)
for those reading this, you obviously want to know what it is. In elder Lyons room you can go through his drawers to find a stash key. A message will pop up saying you should look for anything out of the ordinary in the room. Once you've found what our looking for it will reveal a safe. Open it up and you now have you're very own YK42B PULSE RIFLE!! The pistol can be found in elder Lyons safe along with smugglers end
I'm however just wondering if the pistol intentionally has a higher energy weapon requirement than the rifle. It also has the -10hp effect while the rifle appears to be missing.