Arrows and quarrels are made of two parts: arrowheads
Bowyers in Dereth make different sorts of arrowheads. These are
bought in bundles, as are the shafts to make arrows and quarrels.
If you use arrowheads on arrow shafts, you'll make arrows of the
proper sort: armor-piercing arrowheads will create armor-piercing
arrows, broad arrowheads will make broadhead arrows, and so forth.
A bundle of arrowheads is enough to make ten arrows.
Similarly, using arrowheads on quarrel shafts will make quarrels.
Fletchers are not limited to making mundane arrows and quarrels.
Special oils, created by alchemists, can be used on arrowheads to
give them magical powers. Using Frost Oil on a bundle of arrowheads
will make them into frost arrowheads, for instance. There is also
a particularly potent oil, called Bloodseeker Oil: if you use it
on a bundle of arrowheads, it will change them into greater arrowheads,
which will do more damage.
Be sure to use oils on arrowheads before you use the arrowheads
on shafts (arrow or quarrel), however: once an arrow is made, oils
will no longer affect it.