Sharpen's a world crusher; it almost doubles the damage on a weapon for each level you have in it -- at a cost of +6 or so agility requirement per level. An excellent utility skill.
Definately watch out for 1H vs 1H + Shield; the two are completely similar skills, but as soon as you slap on a shield, all proficiency points you spent in 1H are cancelled. Hopefully, garbage like this gets addressed in a patch...
