The bevel edged chisel has a bevel down the length of the blade on left and right hand side. The purpose is to make the blade lighter easier to use and improve the visibility at the cutting edge. A blade without bevels made just as well would be a firmer chisel and might be used with a mallet for slightly heavier work.
The benefit of the heritage chisel with a bevel is that these bevels were hand cut by a man with a large water cooled grindstone spinning between his legs. He would sit on what was known as an “arseboard” and would grind the wide clean bevels to left and right. These are much better than those found on modern chisels . Why? Well we cannot any more get those poor devils to die in their forties of lung disease! Look at these heritage chisels and admire the skill and workmanship that went into making them . They are no longer being made get this quality hand tool now.