Pearler's Dagger

You gain a +1 bonus to attack and damage rolls
made with this magic weapon.
If the dagger is left in water for 8 consecutive
hours, there is a chance that the blade opens up
at the end of that time to reveal a single white
pearl worth 100 gp. The percent chance to open
is equal to 10 times the highest challenge rating
of any creature slain with the dagger since it was
last left to rest in the water, up to a maximum of
50 percent.
The blade closes again once the pearl is removed.