Yeah, the question with blunt is does it require mind's eye as well? Because then you're into a 20 point investment.
I started thinking of blunt builds for the geode hammer, but the slots on the black belt hammer may be necessary for a zero suit build (blunt, evasion, stamina recovery).
I did the math on the demon visage hammer (280 raw, -70%). With blunt it compares favorably to white sharpness weapons with a bit of affinity. Until you add crit up, then the crit builds win. You could counter the negative affinity with expert and/or weakness exploit, but that would basically be all your points.