Various versions of the Banshee have been described, from a woman with long, red hair and very pale skin to an older woman with stringy, gray hair, rotten teeth and fiery red eyes. She is often depicted with a comb in her hair and this has led to an Irish superstition that finding a comb on the ground is considered bad luck.
Quoted from :
http://www.drakensang.com/Banshees
Another factor that likely contributed to the superstitious legend is the cry of the barn owl. In ancient battles, owls would screech and take flight if they noticed an army approaching, which would forewarn the defending army.