As nouns,
rigger brush is a hyponym of
sable's hair pencil; that is, rigger brush is a
word with a more specific, narrower meaning than
sable's hair pencil:
sable's hair pencil: an artist's brush made of sable hairs
rigger brush: a long slender pointed sable brush used by artists
Other hyponyms of sable's hair pencil include
rigger.