Smuggler Tunnel's secret room

Hello, so in my RotRL AP, with this being my first time playing it, though for the amount of time o have been playing, it is very long over due. So we just got through Tsudo, charmed him and sent him off back to town not dead, and began exploring the tunnels under the Glassworks. While exploring, we found the first split and everyone (but myself and Shalelu) went down the right side, and the two of us went down the left, and I found this secret room with a

and after all that was taken care of properly, I went to collect the nice thing(s) but the GM forgot/couldn't find what it was actually supposed to be, so he substituted it for this Numerian tech piece that transforms into any weapon i desire it to be, and yes, this includes a monowhip and being a Bard I would have proficiency. Meta though, the more I use it in public, the more likely Numerian assassins will hunt me down to reclaim it. All in all, I am really tempted to just sell it, but I want to know if anyone knows what exactly the prize was meant to be? Just so I can see if the DM would prefer sticking to what was supposed to be what.

I... Don't think there was supposed to be any hidden prize where you describe?

I can't understand how it is that your GM couldn't find what was supposed to be in it - how can s/he be running the adventure without this information to hand? In any case, I would speak to your GM first about whether s/he is interested in changing what you found - and, if so, suggest s/he comes here to ask the question.

I'm currently running this adventure for the 2nd time, and

Hmm, perhaps this was all something he made up. But it is his first time DM'ing, and he has been playing for only about two or three years i think. But thank you guys, much appreciated.

As long as you're not running PFS sessions, of course the Dm is free to add anything he wants to a given gaming session, location, critter or loot drop. I'm doing it constantly in my RotRL campaign. Sometimes it's entire sidequests, sometimes it's something as small as an interesting character quirk on an NPC.

If the DM placed a loot drop with a Numerian super-weapon for you to pick up, he either intends you to have and use it, or else he intends to dick around with your character for his own sadistic pleasure. Or both. <g> So just go with the flow, eh?