The ornamental design for a finial, as shown and described.
FIG. 1 is a perspective view from below of a finial in accordance with my design;
FIG. 2 is an enlarged perspective view from below of the finial in accordance with my design;
FIG. 3 is an enlarged side elevation view of the finial in accordance with my design, all side views being substantially identical of that shown; and,
FIG. 4 is an enlarged bottom plan view of the finial in accordance with my design.
The broken line showing of the fan blades, motor housing, light fixture and blade irons is included for the purpose of illustrating environmental structure and forms no part of the claimed design.