Rawr's talon is only obtainable after killing Rawr, an incredibly powerful deathclaw inhabiting the Divide. This variant of a deathclaw hand is the only one of its kind. It is also the only one that can be made into a weapon, the Fist of Rawr.
Rawr is found in a dark cave across from the Boxwood hotel roof, behind the overflowing pipe and irradiated pool. His talon can be taken from his body after defeating him.