So, I'm in the fourteenth century and a UFO approaches? Well, I was thinking about a story set in Jerusalem and having some of the Muslim occupiers slit the throats of the aliens coming down... "We come in peace, we mean you know harm." "Yeah, that's what we said to the infidels, too... KILL THEM!"
Instead, I did a quick search and discovered that a certain holy relic has its origins in that particular page of history...
Pausing a moment during his weekly trip to the market to sell the abbey's wine, Brother Antwelm watched as the lights descended from the sky. BOOM! Every bottle in the donkey cart shattered! Then, a roaring dusty whirlwind surrounded him. When it stopped, a glowing dome appeared on the grass nearby. With a hum, the dome split and a tall figure emerged. Radiant... magnificent... perfect... And on fire! Brother Antwelm grabbed the donkey's cloth blanket and slapped out the fire. Sadly, the magnificent figure was crisped. But his image was fused on the blanket. Antwelm shrugged and continued to Turin.
I'm not sure where I picked the name Antwelm. I may change it to something sillier.