@serval they'd be regular fingernails in their retracted state and would grow longer when protracted. some folks might get them pointy as lots of spooky kids did in the '90s but i'm imagining regular nails with a sharpened edge like a razorblade.
@serval not yet they don't
guess you could also hinge something on the finger at about the last joint that'd flip up when it's cuttin' time but sit palmside otherwise, resting against the second joint. it could look like jewelry. it could be some rings.
@spinach yeah, but fingernails don't have much room to retract?