A big bottle of Titebond II or III is handy to have around the house for lotsa projects. Two or three coats of that will treat the ends quickly enough. Thin it slightly and use a paintbrush to cover the back of the bow if you elect to remove the bark, again two coats will be fine. For that matter, the second coat is really there to hit any spot that might have been missed on the first coat.
Losta guys use lotsa other stuff including latex paint (used that myself with great results), Beeswax, lacquer, tar, rubber cement, and more.