Once you get your knives sharp, go to Fine Firearms in La Mesa and get an AccuSharp knife sharpener. I have several of these because THEY WORK! Just a few strokes on a knife blade or broadhead and it's razor sharp. They're only about $10 or so but they're the best I've ever used.
from the back of the blade you have to lift the edge of the blade and slide it off(away from you) I've actually found its much easier to just break the blade when you want to change it..seems to be a little easier to remove.be careful with these blades because they are SHARP