Toxic Weapon

You touch the weapon, and an oily liquid appears on its surface. When you cast this spell, you coat the target weapon with poison. The next successful melee attack with that weapon delivers the poison. The poison deals 1d10 points of Constitution damage immediately and another 1d10 points of Constitution damage 1 minute later. Each instance of damage can be negated by a Fortitude save (DC equal to this spell's save DC). If the weapon has not scored a successful hit after 1 hour, the poison becomes inert and evaporates.