Don;
Personally, I don't go thru the trouble of "finishing" my hackle pliers, although I totally agree with Buddy on doing so, because sadly,many brands and types are very, very, poorly made and the edges, on the jaws, can really destroy hackle not to mention just cut it in two while you're winding it.
But, instead of finishing, (filing, grinding down and smoothing out the rough and sharp edges), I either slip on a small piece of "shrink tubing", over the jaw or roll on one or two tiny o-rings. Actually, on larger hackles, like Schlappen, I prefer to use the o-rings.
Saint Paul-"The Highly Confused"
You cannot do a kindness too soon, for you never know how soon it will be too late.
-- Ralph Waldo Emerson