Rapiers have an entire set of original unused sounds, Bilsy has a couple, there's the stoned sound that's never played, and pretty sure neither is the fan sound. The glove sound is obviously unused because so is the glove. I think several other objects have unused sounds too, I believe Bolly and Uterus bosses have one each and there are probably more I missed, for example I'm not entirely convinced Devan plays the entire set of his sounds but I didn't actually check. We might someday let some of them play, probably those whose purpose is clear and won't require changing game mechanics, but it sounds like something we'd do when extremely bored.