I just received my 710 in M390 and it seems pretty fairly sharpened it can shave quite easily although its not hair popping by any means would the sharpmaker maintain this steel if it I kept it sharp? the edge its at is fine but whats the sharpest the fine stone will get a knife? I don't want to drop another 40 on the the diamond and ultrafine stones as all my knives already have some degree of sharpness and I only want an edge maybe slightly above shaving.