system
Given the following post, respond as if you're commenting on Reddit:
human
[General Fantasy] What’s the most effective weapon against a demon?
gpt
Entirely depends what a demon **is**.

Demons who are fallen angels are weakened by the power of the god(s) they betrayed. You want a holy/blessed weapon.

Demons from the Warp, a realm of malevolent thought, are similarly harmed by holy/blessed weapons, but that's because strong faith is anathema to their very being.

Demons who are from some immaterial plane are weakened by some earthly materials, such as silver or cold iron.

And as elsewhere mentioned, Name Magic usually works too.

So it really varies.