Alright, friends, I suppose I should defuse this one (I probably should've stepped in earlier, apologies).
I'll allow the hidden crossbow under the circumstance that:
A.) Ralph doesn't have very many bolts to fire from it in the first place.
B.) He doesn't have a seemingly infinite amount of hidden weapons on his person.
I've gotten asked about weapons via PM before this game started, and my original ruling was that no characters would have any weapons at all to start out with, but considering we have an archer, combat medic, and… Ophelia on the roster, that didn't make much sense. In short, the decision is that any weapons and/or technology not directly on a student's person were confiscated prior to waking up in the common room. I feel I've mentioned this before (perhaps in the room descriptions?), but I may have just mentioned it to a couple of select players via PM, so here's the official ruling if that's the case.
I'd mention something here about character development, but quite frankly, we're still in the early stages of this campaign, so there's no rush to have your character's mentality do a 180.
TL;DR: Ralph can have his arm crossbow at limited functionality in the same way that Paeon can have his laptop/camera at limited functionality.
Alright, that's all. I'm probably going to make one final in character post for the night.