Long-bladed throwing weapons used by Assassins such as Teppic. These were concealed in velvet sheaths in his boots.
From context, these are not the Western image of shurikens, more just a blade, or Bo Shuriken, such as those shown here: [[1]].
![[1]](http://www.bokken-shop.com/shop/picture/ninja%20shuriken.jpg){kind=link}