You take a swing at it, but you're unused to the sword and it misses the body of the spider and hits the floor, knocking up bone dust.
The spider raises its forelegs in your direction, wriggling them. Then its mandibles open to release an unnerving hiss. For a moment it seems about to attack, then it pivots around, spinning directly away from you before it scuttles out of the light with remarkable speed.
"That wasn't very impressive."
"It ran away." You look for the spider, but it's vanished into the darkness beyond the reach of the sword's glow.
"You let it escape."
"It's just a big spider." You turn back toward the breeze, and hopefully the exit.
"That wasn't just a spider."
You pause as you're just about to take a step forward. "What do you mean it wasn't 'just' a spider?"
"That was a malevolent creature of the darkness, exactly the sort of evil I was forged to slay."
"So you're a spider-slaying sword?"
"You aren't listening."
The sword's right, you aren't listening. You're hearing the skittering again, and you're trying to determine which direction it's coming from.