Without knowing what edition and what point buy species calculator you're working with, it's hard to answer, but I'll give my general opinion. Since 1d6 is kind of baseline "light weapon" damage, it's really just giving someone an undisarmable mace/light mace. In old 3E terms, undisarmable worked out to a 1 point adjustment in weapon balance calculators.
It's not really a huge ability. If it's light and can be dual wielded, it will see some use on fighters. If it's finessable, rogues will use it. Otherwise, it's not a huge ability, as most everyone has mace proficiency.