A simple yet useful addition to a knife is file jimping.  A slight texture applied to the spine of a knife where one may place their thumb while working a feather stick or doing small, more controled tasks. 
 
This style of file jimping can be added to a jasper, Coyote Works 1.0, A Coyote Works "Pup", A bush knife, or any other knife that has more of a stright spine.