Reforge

Try waving your artifact around and wishing you were actually clean, then go down and confront them.

You vaguely wield the jar while wishing you were clean and... what were you doing again? Hey- it looks like the jar is making those rings again. Does that mean that it's hiding something or whatever it does? You tell it to deactivate it and-

SpoilerShow

Oh, right! You had used it to hide the stains and rips. Hmm. It appears that if you make something 'hidden' with the jar, you can't perceive it either. And given that 'hiding' the damage was how it reacted to 'make me clean', you're starting to get the sense that however this thing works, it can't make actual, permanent changes to reality. Maybe there's a way around these limitations, but frankly you haven't the faintest clue of how this thing works and yes, you are concerned about that.

.>Firsthave a prty of guards greet (and suround) them see how they presnt themselves.

You send a group of guards out to meet with Four Corners and ask them their business here- while making it very clear who holds the power in the exchange.

??????: ...looks like they're spooked.
????: Perhaps. I'll admit that this response is perhaps a bit much, but there are innumerable, perfectly legitimate reasons for them to be wary.
????: Well, no need to be standoffish-
????: Providence upon you, good fellows! I shall of course answer where I may regarding our purpose in coming to your, may I say, magnificent Teneogris...

>Have your knight bring you a clean coat and a bassin of water t clean your face and arms. Doesn't have to be the fanciest but just good enough and big enough to cover most of the ripped and stained clothes
>Viezer: Prepare to do your oh so delicate balancing act job of smoothing things ove should it be needed without overstepping the firsborn authority

You get as presentable as you can while you wait to hear back from the retinue you sent out. The pair say they're here seeking information about the summoning, and to 'offer their services' if need be. Sounds like they're aiming to do something inside your city, possibly hinging on meeting with your Vizier since they're specifically seeking audience with them. You're going to head on down and confront them yourself- but, unfortunately, it looks like you gave your aforementioned advisor time to catch up with you.

Vizier: Firstborn! Please! I beg of you to hold for just a moment!
This is bad. If you snub them, you might meet more resistance later. But if you quail or get turned away now? You’ll have established first thing after assuming control here that you can be second-guessed, that you'll do foolish things, that they can or even must control and influence you.
What will you do? Assert your dominance and carry on? Or weaken your authority to ease your relationship?