The ornamental design for a finial, as shown and described.
FIG. 1 is a perspective view of a finial;
FIG. 2 is a bottom plan view of the finial of FIG. 1;
FIG. 3 is a top plan view of the finial of FIG. 1;
FIG. 4 is a front elevational view of the finial of FIG. 1; and,
FIG. 5 is a left side elevational view of the finial of FIG. 1.
The back elevational view is a mirror image the front elevational view. The right side elevational view is a mirror image the left side elevational view.
The broken lines in the drawings illustrate portions of the finial which form no part of the claimed design.