So take a creature like a werewolf or a Fallout deathclaw. Either through evolution or genetic engineering has claws with a graphene edge instead of keratin. The claws work like a more organic version of the hacksaw answer. The top part of the claws has a soft tissue center that can produce more graphene to maintain the graphene ribbon, so the claws overall do have some thickness to them. Assuming the claws are long enough, could a creature using its full force of a swipe penetrate steel plate-mail armor?
If it can then lets up the ante...
Can the same claw (but longer) cut through the steel armor of a modern tank?
One of the challenges I see in general for the scenarios is that the animal's body is relatively normal, and so it has a limit of the amount of force it can exert. So even if the claws are strong enough to handle the force needed to pull it off, the paw might not be able to deliver it.
A second challenge I foresee with the tank scenario is that even if the claws could penetrate they could get wedged while attempting to cut through. Would that be the case? If so is there any way to overcome it?