system
Given the following post, respond as if you're commenting on Reddit:
human
[The Princess Bride] What's a holocaust cloak?
gpt
>holocaust: destruction or slaughter on a mass scale, esp. caused by fire or nuclear war

The name derives from the "fire" part.  It's a cloak made of a fairly thick, mostly non-flammable fabric.

The Dread Pirate Roberts figured out that if you run a razor aligned perpendicular to the direction you're running it along the outside of the cloak you can fray the fibers just enough that the cloak gets a little bit of a fuzzy aura.  This fuzziness - unlike the rest of the cloak - is highly flammable (sort like how flour is highly combustible only if widely dispersed).  But, because of the specific fabric its made of, the small loose ends will burn for longer than you'd expect: about 30 seconds to a minute.  

It's a neat party trick, but you have to be very careful when wearing it while lit.  Basically, you have to stay as still as possible or else you might burn your hands/legs/face.

This is why the Dread Pirate needed a cart to push around his Giant, and why he had to delay lighting it for dramatic effect.