Steelsting

This spell brings into being a brief maelstrom of dagger-like flying darts of enchanted force, that whirl and flash about within the spell’s area of effect, slicing all creatures they come into contact with for 6d4 hp damage. Victims who are free to move out of the area of effect are allowed a saving throw vs. spell (if successful, they suffer only half damage), but victims who are constrained (for example, beings in a narrow passageway, or who are climbing a ladder or tethered to a heavy weight) against agile dodging or an ability to get out of the area of effect receive no such saving throw.

The blade-like “darts” the spell creates are emissions of a whirling magical field, not metal weapons or anything that can be considered a solid, “normal” missile. Shields and armor can’t stop them, though a wall or closed door can; rather than ricocheting off a partial barrier such as a shield, a dart simply “dissolves” back into the field and flares into sharpness again on the other side of the barrier.