I have a set of kitchen knives of unknown quality that are in need of sharpening. I bought a no-frills sharpener that just has two slots with instructions to hold the blade against one side and slide it through a few times, then repeat on the second slot. There are stones set at an angle that I can feel grinding as I do this. Doesn't seem to have much effect, though. After doing this, they can't cut through a sheet of paper. FYI, the brand is "Tedron Swords", if that means anything. Anybody got some recommendations?