10 or 15 splintering weapons are usually only valueable if the other mods are really heavy, like to the point where it would be a good weapon even if it had no splintering.
Like, if that 15 splinter butcher also had 50 hit lightning 50 hld it would hold some good value. Someone might use it as is, but with 30 splinter items becoming more common not many will want to use a low splinter item.