Fire Arrows
From The DarkMod Wiki
Fire arrows cause a significant explosion that will fling movable objects around.
Tactics and strategies
Fire arrows will cause flamable objects, like unlit torches or candles, to ignite.
A fire arrow makes a massive amount of noise, so use it only when you're not worried about being caught.
Stealth considerations
Having a fire arrow selected as your current weapon makes you very easy to see.
In-game description
Fire arrow: Used primarily by elite mercenaries, these will explode violently on impact. The tip glows and is easily seen in the dark.