The ornamental design for a knifeblade, as shown and described.
FIG. 1 is a perspective view of the blade of my new design;
FIG. 2 is a front end view of the blade of my new design;
FIG. 3 is a rear end view of the blade of my new design;
FIG. 4 is a right side view of the blade of my new design;
FIG. 5 is a left side view of the blade of my new design;
FIG. 6 is a top view of the blade of my new design;
FIG. 7 is a bottom view of the blade of my new design;
FIG. 8 is a right side view of the blade of my new design illustrated in a closing position with respect to an exemplary knife handle with phantom shown as see through; and,
FIG. 9 is a right side view of the blade of my new design illustrated in a closed position with respect to an exemplary knife handle with phantom shown as see through.
The broken lines depictions of the handle are provided for environmental purposes and form no part of the claimed design.