I would probably have to agree that it's somewhere where the player can't see. But then it makes me wonder why it's not present. I feel like that would be aesthetically appealing to see that mounted nicely somewhere, and then the player has the ultimate luxury of rolling in such a classy way, to obtain said scabbard/sheath.
I for one would at least incorporate that kind of thing in a game like Cardinal Kingdom, given all the different swords there are (and they are in no way small variations). As for different scabbards/sheaths, I have you start out with the Master Sword, so you would already be shown with at least its sheath. Perhaps it would "disappear" if other swords were equipped since I don't think the giant Stone Sword would fit (similar to Ike's ala Super Smash Bros).