I claim the ornamental design for a bar knife, as shown and described.
FIG. 1 is a left side elevation of a handle and blade for a bar shucking knife, wherein the right side elevation (not shown) is a mirror image of the left side elevation FIG. 1 of my design;
FIG. 2 is a top plan view, wherein the bottom plan view (not shown) is a mirror image of the top plan view FIG. 2;
FIG. 3 is a front elevation view of my design; and,