“Any one is wantink a good high quality toy soldier? Eh? Eh? ehhh? Makes the liddle children very happy, no? Eh? eh?”
“Master Weaponsmith, we come from ____. We have discovered an evil weapon that must be destroyed as soon as possible. May we use your forge for this?”
“I am Cella, a priestess of Peony, please help us.”
sputter “Wha? Evil weapon? You been drinkin’?”
If only that were so. The dagger in this box reaches out to men’s minds and urges them to evil acts. All of us can attest to it.
Cella believes it to be an artifact from an evil cult.
“Let’s see it, then.”
How about you see it while our smithy here melts it down. You heard the part about “urging to evil acts,” right?
“I don’t want nothin’ evil in my forge. What if it breaks my forge or turns it evil? That would cost me a lot of… money.”
"I believe that my friend was mistaken, evil things have been done with this knife but it is not evil itself. But our lord doesn’t want it to be celebrated by those who have done the evil acts and so he wants to destroy it.
You can see we are not the mighty warriors that would be sent to guard a weapon of true evil."
He looks at you dubiously, then looks at the fire, then looks back at you. “Throw it in.”
Do I have any blessing covering the destruction of cult artifacts? 
I’ll say some generic blessings to keep good thoughts in the front of everyone’s minds.
Generic is pretty much what you have.
Symon reaches down and unlocks the chest so he can remove the knife. He picks it up with the tongs so he can place it in the hottest part of the fire. Once he’s done he steps behind Cella just in case.
Are the forge folks manning the bellows to get things good and hot? If they look reluctant, I could start pumping. Hotter is better.
They’re working hard at it, almost taking a little joy in it. Some time later (no idea how long this would take), the dagger is destroyed and everyone’s mood lifts a little. You almost feel like a group hug.
Ingmar is confused.
Where is Ingmar? Is Ingmar with the box? Bork? Bork? Bork?
“Yay!”
“Thank you, [[weaponsmith’s name]]. Can you turn the scrapped metal into something innocuous, like nails or horseshoes, instead of another weapon?”
“Do we have time to head back, or should we stay the night here?”
“Glad that’s over with! If there’s time to head back, I think we let everyone know that the dagger’s been destroyed.”
We didn’t get here until near noon. Then we had to wait for Master Geoffry’s return, then the melting. I don’t think we’ll make it back before dark. And it’s probably still raining.
I suggest we stay at the Inn and return in the morning.
It’s already night time. And there’s room at the inn.