The difference that I don't think you're understanding is:
Having a second sword (when sheathed) on your hip when in 3rd person view is aesthetic. It would be for looks only and does not affect gameplay.
The Jeweled Carafe (or whatever it is) is an actual part of a Thieves Guild side quest. Therefore it's more important because it actually affects something in the game other than someone's delicate sensibilities.
This is why something like not being able to see the second sword is most likely near the bottom of the Devs honey-do list.
So is the pitcher apparently. I've been emailing Bethesda and PMing Gstaff every time a new patch comes out, asking if it's possible for them to fix the bugs for the Thieves' Guild (Brand-Shei, Nightingale Blade, Pitcher, Litany of Larceny etc.) and each time they tell me they'll pass my note along. So then I wait for a month or two, and new patch notes get released, and I see they didn't fix what I was asking about, so I message them both again, asking if these things might be added while the patch is still in beta. That doesn't work out either, so then I message them again after the new patch is released, asking if they'll please, please, please try to address these problems in the following patch.
I've been doing this since 1.2, and I still haven't seen these things addressed.