How do you loosen stuck bolts holding Honda mower blade?

A breaker Bar. They are available at your local automotive store. My daughter bought me one for a gift at Harbor Freight tools for about ten bucks. It is the most used tool I own. It has made removing stuck nuts and bolts a real breeze. I cannot believe I struggled with frozen mower blade bolts for so many years before the breaker bar. Caution, use gloves and a piece of wood to wedge against the blade to keep it stationary while you turn the nut. Also, remove the plug wire from the spark plug, of course.