Most will do the trick. The key is simply keeping a consistent angle and moving to finer and finer grits. Some also strop their blades using jeweler's rouge and a piece of leather. I don't find it particularly necessary, though it does help. I use Slick Tricks, and touch them up by using one of the Smith's handheld carbide sharpeners (similar to an Accusharp). Works well enough by using very light pressure.

I also use the Accusharp that RiverOtter mentioned. I polish it off by stropping the blades on leather.....puts a great edge on Slick Tricks.

Having said this, I have a theory that putting an extra sharp edge on an already sharp broadhead is overkill....mainly a confidence enhancer which we all like. Any other thoughts on this?

Yeah, my thought is that is impossible to have a BH that is too sharp. In fact, there is no such thing, that term doesn't exist. Blood clots easier on a jagged edge than a smooth one, because there is more surface area. Therefore, an animal shot w/ a sharp BH will bleed out more, and faster, than one shot w/ a dull BH.