The skill required in using bladed scarves effectively and not revealing their deadly nature makes them exotic weapons.
If you are proficient with a bladed scarf, you deal 1d4 points of slashing damage to any creature that makes a successful grapple check against you while you wield the scarf.
Pathfinder Campaign Setting: The Inner Sea World Guide. © 2011, Paizo Publishing, LLC; Authors: Keith Baker, Wolfgang Baur, Clinton J. Boomer, Jason Bulmahn, Joshua J. Frost, Ed Greenwood, Stephen S. Greer, Jeff Grubb, James Jacobs, Michael Kortes, Tito Leati, Mike McArtor, Rob McCreary, Erik Mona, Jason Eric Nelson, Jeff Quick, Sean K Reynolds, F. Wesley Schneider, Leandra Christine Schneider, David Schwartz, Amber E. Scott, Stan!, Owen K.C. Stephens, Todd Stewart, James L. Sutter, Greg A. Vaughan, Jeremy Walker, and JD Wiker.