Research (ie 2 tests that show the same result under different circumstances) indicates that the oilstone can only repair up to 99%, or it can repair beyond this, but only from a lower condtion. You cannot repair from 99% condition to a better condition. In this case, a copper short sword was honed to a value of 693. In perfect condition, it has a value of 700. And an Axe of Managerial Ire was honed to a value of 2475, where in perfect condition it values at 2500.