Slight of Hand Most quivers are about 3/4 the size of the wearer's back so it can hold the arrows. Most people would say this is well more than the size of a hand crossbow. An arrow is also significantly larger than a dart. By raw, it is not possible to hide your standard, mundane quiver.
Perhaps there are some magic items that do that (such as bag of holding, which you can then hide), but not the mundane one.
Of course...you could try and "misread" the chart that says "Lift a small object from a person", since "small" in D&D is 1/2 the size of a human, a quiver would fit that description. But then your DM's just going to "misread" that as saying you now need to make that check just to carry it, not conceal it.
If you go with epic sleight of hand, or magic, then you could, but I think you already figured this out.