For longer blades you can just reposition the sharperner guide to a new spot on the blade and continue sharpening as norma. Personally I like Diamond and Ceramic "stones" they last forever and don't dish out like conventional stones will do. As for "the angle" I have just developed my own over many many years of freehand sharpening and can sharpen just by "feel" and by the "sound" the steel makes over the stone. But as "they' say, Practice Practice Practice.